Merge pull request #2742 from karalabe/tx-spam-protection

Transaction pool optimizations

15 files changed, 1146 insertions, 553 deletions

diff --git a/core/tx_list.go b/core/tx_list.go
new file mode 100644
index 000000000..c3ddf3148
--- /dev/null
+++ b/core/tx_list.go
@@ -0,0 +1,342 @@
+// Copyright 2016 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+package core
+
+import (
+	"container/heap"
+	"math"
+	"math/big"
+	"sort"
+
+	"github.com/ethereum/go-ethereum/core/types"
+)
+
+// nonceHeap is a heap.Interface implementation over 64bit unsigned integers for
+// retrieving sorted transactions from the possibly gapped future queue.
+type nonceHeap []uint64
+
+func (h nonceHeap) Len() int           { return len(h) }
+func (h nonceHeap) Less(i, j int) bool { return h[i] < h[j] }
+func (h nonceHeap) Swap(i, j int)      { h[i], h[j] = h[j], h[i] }
+
+func (h *nonceHeap) Push(x interface{}) {
+	*h = append(*h, x.(uint64))
+}
+
+func (h *nonceHeap) Pop() interface{} {
+	old := *h
+	n := len(old)
+	x := old[n-1]
+	*h = old[0 : n-1]
+	return x
+}
+
+// txSortedMap is a nonce->transaction hash map with a heap based index to allow
+// iterating over the contents in a nonce-incrementing way.
+type txSortedMap struct {
+	items map[uint64]*types.Transaction // Hash map storing the transaction data
+	index *nonceHeap                    // Heap of nonces of all the stored transactions (non-strict mode)
+	cache types.Transactions            // Cache of the transactions already sorted
+}
+
+// newTxSortedMap creates a new sorted transaction map.
+func newTxSortedMap() *txSortedMap {
+	return &txSortedMap{
+		items: make(map[uint64]*types.Transaction),
+		index: &nonceHeap{},
+	}
+}
+
+// Get retrieves the current transactions associated with the given nonce.
+func (m *txSortedMap) Get(nonce uint64) *types.Transaction {
+	return m.items[nonce]
+}
+
+// Put inserts a new transaction into the map, also updating the map's nonce
+// index. If a transaction already exists with the same nonce, it's overwritten.
+func (m *txSortedMap) Put(tx *types.Transaction) {
+	nonce := tx.Nonce()
+	if m.items[nonce] == nil {
+		heap.Push(m.index, nonce)
+	}
+	m.items[nonce], m.cache = tx, nil
+}
+
+// Forward removes all transactions from the map with a nonce lower than the
+// provided threshold. Every removed transaction is returned for any post-removal
+// maintenance.
+func (m *txSortedMap) Forward(threshold uint64) types.Transactions {
+	var removed types.Transactions
+
+	// Pop off heap items until the threshold is reached
+	for m.index.Len() > 0 && (*m.index)[0] < threshold {
+		nonce := heap.Pop(m.index).(uint64)
+		removed = append(removed, m.items[nonce])
+		delete(m.items, nonce)
+	}
+	// If we had a cached order, shift the front
+	if m.cache != nil {
+		m.cache = m.cache[len(removed):]
+	}
+	return removed
+}
+
+// Filter iterates over the list of transactions and removes all of them for which
+// the specified function evaluates to true.
+func (m *txSortedMap) Filter(filter func(*types.Transaction) bool) types.Transactions {
+	var removed types.Transactions
+
+	// Collect all the transactions to filter out
+	for nonce, tx := range m.items {
+		if filter(tx) {
+			removed = append(removed, tx)
+			delete(m.items, nonce)
+		}
+	}
+	// If transactions were removed, the heap and cache are ruined
+	if len(removed) > 0 {
+		*m.index = make([]uint64, 0, len(m.items))
+		for nonce, _ := range m.items {
+			*m.index = append(*m.index, nonce)
+		}
+		heap.Init(m.index)
+
+		m.cache = nil
+	}
+	return removed
+}
+
+// Cap places a hard limit on the number of items, returning all transactions
+// exceeding that limit.
+func (m *txSortedMap) Cap(threshold int) types.Transactions {
+	// Short circuit if the number of items is under the limit
+	if len(m.items) <= threshold {
+		return nil
+	}
+	// Otherwise gather and drop the highest nonce'd transactions
+	var drops types.Transactions
+
+	sort.Sort(*m.index)
+	for size := len(m.items); size > threshold; size-- {
+		drops = append(drops, m.items[(*m.index)[size-1]])
+		delete(m.items, (*m.index)[size-1])
+	}
+	*m.index = (*m.index)[:threshold]
+	heap.Init(m.index)
+
+	// If we had a cache, shift the back
+	if m.cache != nil {
+		m.cache = m.cache[:len(m.cache)-len(drops)]
+	}
+	return drops
+}
+
+// Remove deletes a transaction from the maintained map, returning whether the
+// transaction was found.
+func (m *txSortedMap) Remove(nonce uint64) bool {
+	// Short circuit if no transaction is present
+	_, ok := m.items[nonce]
+	if !ok {
+		return false
+	}
+	// Otherwise delete the transaction and fix the heap index
+	for i := 0; i < m.index.Len(); i++ {
+		if (*m.index)[i] == nonce {
+			heap.Remove(m.index, i)
+			break
+		}
+	}
+	delete(m.items, nonce)
+	m.cache = nil
+
+	return true
+}
+
+// Ready retrieves a sequentially increasing list of transactions starting at the
+// provided nonce that is ready for processing. The returned transactions will be
+// removed from the list.
+//
+// Note, all transactions with nonces lower than start will also be returned to
+// prevent getting into and invalid state. This is not something that should ever
+// happen but better to be self correcting than failing!
+func (m *txSortedMap) Ready(start uint64) types.Transactions {
+	// Short circuit if no transactions are available
+	if m.index.Len() == 0 || (*m.index)[0] > start {
+		return nil
+	}
+	// Otherwise start accumulating incremental transactions
+	var ready types.Transactions
+	for next := (*m.index)[0]; m.index.Len() > 0 && (*m.index)[0] == next; next++ {
+		ready = append(ready, m.items[next])
+		delete(m.items, next)
+		heap.Pop(m.index)
+	}
+	m.cache = nil
+
+	return ready
+}
+
+// Len returns the length of the transaction map.
+func (m *txSortedMap) Len() int {
+	return len(m.items)
+}
+
+// Flatten creates a nonce-sorted slice of transactions based on the loosely
+// sorted internal representation. The result of the sorting is cached in case
+// it's requested again before any modifications are made to the contents.
+func (m *txSortedMap) Flatten() types.Transactions {
+	// If the sorting was not cached yet, create and cache it
+	if m.cache == nil {
+		m.cache = make(types.Transactions, 0, len(m.items))
+		for _, tx := range m.items {
+			m.cache = append(m.cache, tx)
+		}
+		sort.Sort(types.TxByNonce(m.cache))
+	}
+	// Copy the cache to prevent accidental modifications
+	txs := make(types.Transactions, len(m.cache))
+	copy(txs, m.cache)
+	return txs
+}
+
+// txList is a "list" of transactions belonging to an account, sorted by account
+// nonce. The same type can be used both for storing contiguous transactions for
+// the executable/pending queue; and for storing gapped transactions for the non-
+// executable/future queue, with minor behavoiral changes.
+type txList struct {
+	strict  bool         // Whether nonces are strictly continuous or not
+	txs     *txSortedMap // Heap indexed sorted hash map of the transactions
+	costcap *big.Int     // Price of the highest costing transaction (reset only if exceeds balance)
+}
+
+// newTxList create a new transaction list for maintaining nonce-indexable fast,
+// gapped, sortable transaction lists.
+func newTxList(strict bool) *txList {
+	return &txList{
+		strict:  strict,
+		txs:     newTxSortedMap(),
+		costcap: new(big.Int),
+	}
+}
+
+// Add tries to insert a new transaction into the list, returning whether the
+// transaction was accepted, and if yes, any previous transaction it replaced.
+//
+// If the new transaction is accepted into the list, the lists' cost threshold
+// is also potentially updated.
+func (l *txList) Add(tx *types.Transaction) (bool, *types.Transaction) {
+	// If there's an older better transaction, abort
+	old := l.txs.Get(tx.Nonce())
+	if old != nil && old.GasPrice().Cmp(tx.GasPrice()) >= 0 {
+		return false, nil
+	}
+	// Otherwise overwrite the old transaction with the current one
+	l.txs.Put(tx)
+	if cost := tx.Cost(); l.costcap.Cmp(cost) < 0 {
+		l.costcap = cost
+	}
+	return true, old
+}
+
+// Forward removes all transactions from the list with a nonce lower than the
+// provided threshold. Every removed transaction is returned for any post-removal
+// maintenance.
+func (l *txList) Forward(threshold uint64) types.Transactions {
+	return l.txs.Forward(threshold)
+}
+
+// Filter removes all transactions from the list with a cost higher than the
+// provided threshold. Every removed transaction is returned for any post-removal
+// maintenance. Strict-mode invalidated transactions are also returned.
+//
+// This method uses the cached costcap to quickly decide if there's even a point
+// in calculating all the costs or if the balance covers all. If the threshold is
+// lower than the costcap, the costcap will be reset to a new high after removing
+// expensive the too transactions.
+func (l *txList) Filter(threshold *big.Int) (types.Transactions, types.Transactions) {
+	// If all transactions are below the threshold, short circuit
+	if l.costcap.Cmp(threshold) <= 0 {
+		return nil, nil
+	}
+	l.costcap = new(big.Int).Set(threshold) // Lower the cap to the threshold
+
+	// Filter out all the transactions above the account's funds
+	removed := l.txs.Filter(func(tx *types.Transaction) bool { return tx.Cost().Cmp(threshold) > 0 })
+
+	// If the list was strict, filter anything above the lowest nonce
+	var invalids types.Transactions
+	if l.strict && len(removed) > 0 {
+		lowest := uint64(math.MaxUint64)
+		for _, tx := range removed {
+			if nonce := tx.Nonce(); lowest > nonce {
+				lowest = nonce
+			}
+		}
+		invalids = l.txs.Filter(func(tx *types.Transaction) bool { return tx.Nonce() > lowest })
+	}
+	return removed, invalids
+}
+
+// Cap places a hard limit on the number of items, returning all transactions
+// exceeding that limit.
+func (l *txList) Cap(threshold int) types.Transactions {
+	return l.txs.Cap(threshold)
+}
+
+// Remove deletes a transaction from the maintained list, returning whether the
+// transaction was found, and also returning any transaction invalidated due to
+// the deletion (strict mode only).
+func (l *txList) Remove(tx *types.Transaction) (bool, types.Transactions) {
+	// Remove the transaction from the set
+	nonce := tx.Nonce()
+	if removed := l.txs.Remove(nonce); !removed {
+		return false, nil
+	}
+	// In strict mode, filter out non-executable transactions
+	if l.strict {
+		return true, l.txs.Filter(func(tx *types.Transaction) bool { return tx.Nonce() > nonce })
+	}
+	return true, nil
+}
+
+// Ready retrieves a sequentially increasing list of transactions starting at the
+// provided nonce that is ready for processing. The returned transactions will be
+// removed from the list.
+//
+// Note, all transactions with nonces lower than start will also be returned to
+// prevent getting into and invalid state. This is not something that should ever
+// happen but better to be self correcting than failing!
+func (l *txList) Ready(start uint64) types.Transactions {
+	return l.txs.Ready(start)
+}
+
+// Len returns the length of the transaction list.
+func (l *txList) Len() int {
+	return l.txs.Len()
+}
+
+// Empty returns whether the list of transactions is empty or not.
+func (l *txList) Empty() bool {
+	return l.Len() == 0
+}
+
+// Flatten creates a nonce-sorted slice of transactions based on the loosely
+// sorted internal representation. The result of the sorting is cached in case
+// it's requested again before any modifications are made to the contents.
+func (l *txList) Flatten() types.Transactions {
+	return l.txs.Flatten()
+}
diff --git a/core/tx_list_test.go b/core/tx_list_test.go
new file mode 100644
index 000000000..92b211937
--- /dev/null
+++ b/core/tx_list_test.go
@@ -0,0 +1,52 @@
+// Copyright 2016 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+package core
+
+import (
+	"math/big"
+	"math/rand"
+	"testing"
+
+	"github.com/ethereum/go-ethereum/core/types"
+	"github.com/ethereum/go-ethereum/crypto"
+)
+
+// Tests that transactions can be added to strict lists and list contents and
+// nonce boundaries are correctly maintained.
+func TestStrictTxListAdd(t *testing.T) {
+	// Generate a list of transactions to insert
+	key, _ := crypto.GenerateKey()
+
+	txs := make(types.Transactions, 1024)
+	for i := 0; i < len(txs); i++ {
+		txs[i] = transaction(uint64(i), new(big.Int), key)
+	}
+	// Insert the transactions in a random order
+	list := newTxList(true)
+	for _, v := range rand.Perm(len(txs)) {
+		list.Add(txs[v])
+	}
+	// Verify internal state
+	if len(list.txs.items) != len(txs) {
+		t.Errorf("transaction count mismatch: have %d, want %d", len(list.txs.items), len(txs))
+	}
+	for i, tx := range txs {
+		if list.txs.items[tx.Nonce()] != tx {
+			t.Errorf("item %d: transaction mismatch: have %v, want %v", i, list.txs.items[tx.Nonce()], tx)
+		}
+	}
+}
diff --git a/core/tx_pool.go b/core/tx_pool.go
index 596356377..f8b11a7ce 100644
--- a/core/tx_pool.go
+++ b/core/tx_pool.go
@@ -45,8 +45,11 @@ var (
 	ErrNegativeValue      = errors.New("Negative value")
 )
 
-const (
-	maxQueued = 64 // max limit of queued txs per address
+var (
+	maxQueuedPerAccount = uint64(64)    // Max limit of queued transactions per address
+	maxQueuedInTotal    = uint64(65536) // Max limit of queued transactions from all accounts
+	maxQueuedLifetime   = 3 * time.Hour // Max amount of time transactions from idle accounts are queued
+	evictionInterval    = time.Minute   // Time interval to check for evictable transactions
 )
 
 type stateFn func() (*state.StateDB, error)
@@ -68,10 +71,14 @@ type TxPool struct {
 	events       event.Subscription
 	localTx      *txSet
 	mu           sync.RWMutex
-	pending      map[common.Hash]*types.Transaction // processable transactions
-	queue        map[common.Address]map[common.Hash]*types.Transaction
 
-	wg sync.WaitGroup // for shutdown sync
+	pending map[common.Address]*txList         // All currently processable transactions
+	queue   map[common.Address]*txList         // Queued but non-processable transactions
+	all     map[common.Hash]*types.Transaction // All transactions to allow lookups
+	beats   map[common.Address]time.Time       // Last heartbeat from each known account
+
+	wg   sync.WaitGroup // for shutdown sync
+	quit chan struct{}
 
 	homestead bool
 }
@@ -79,8 +86,10 @@ type TxPool struct {
 func NewTxPool(config *ChainConfig, eventMux *event.TypeMux, currentStateFn stateFn, gasLimitFn func() *big.Int) *TxPool {
 	pool := &TxPool{
 		config:       config,
-		pending:      make(map[common.Hash]*types.Transaction),
-		queue:        make(map[common.Address]map[common.Hash]*types.Transaction),
+		pending:      make(map[common.Address]*txList),
+		queue:        make(map[common.Address]*txList),
+		all:          make(map[common.Hash]*types.Transaction),
+		beats:        make(map[common.Address]time.Time),
 		eventMux:     eventMux,
 		currentState: currentStateFn,
 		gasLimit:     gasLimitFn,
@@ -88,10 +97,12 @@ func NewTxPool(config *ChainConfig, eventMux *event.TypeMux, currentStateFn stat
 		pendingState: nil,
 		localTx:      newTxSet(),
 		events:       eventMux.Subscribe(ChainHeadEvent{}, GasPriceChanged{}, RemovedTransactionEvent{}),
+		quit:         make(chan struct{}),
 	}
 
-	pool.wg.Add(1)
+	pool.wg.Add(2)
 	go pool.eventLoop()
+	go pool.expirationLoop()
 
 	return pool
 }
@@ -117,7 +128,7 @@ func (pool *TxPool) eventLoop() {
 			pool.minGasPrice = ev.Price
 			pool.mu.Unlock()
 		case RemovedTransactionEvent:
-			pool.AddTransactions(ev.Txs)
+			pool.AddBatch(ev.Txs)
 		}
 	}
 }
@@ -125,12 +136,12 @@ func (pool *TxPool) eventLoop() {
 func (pool *TxPool) resetState() {
 	currentState, err := pool.currentState()
 	if err != nil {
-		glog.V(logger.Info).Infoln("failed to get current state: %v", err)
+		glog.V(logger.Error).Infof("Failed to get current state: %v", err)
 		return
 	}
 	managedState := state.ManageState(currentState)
 	if err != nil {
-		glog.V(logger.Info).Infoln("failed to get managed state: %v", err)
+		glog.V(logger.Error).Infof("Failed to get managed state: %v", err)
 		return
 	}
 	pool.pendingState = managedState
@@ -139,26 +150,21 @@ func (pool *TxPool) resetState() {
 	// any transactions that have been included in the block or
 	// have been invalidated because of another transaction (e.g.
 	// higher gas price)
-	pool.validatePool()
-
-	// Loop over the pending transactions and base the nonce of the new
-	// pending transaction set.
-	for _, tx := range pool.pending {
-		if addr, err := tx.From(); err == nil {
-			// Set the nonce. Transaction nonce can never be lower
-			// than the state nonce; validatePool took care of that.
-			if pool.pendingState.GetNonce(addr) <= tx.Nonce() {
-				pool.pendingState.SetNonce(addr, tx.Nonce()+1)
-			}
-		}
+	pool.demoteUnexecutables()
+
+	// Update all accounts to the latest known pending nonce
+	for addr, list := range pool.pending {
+		txs := list.Flatten() // Heavy but will be cached and is needed by the miner anyway
+		pool.pendingState.SetNonce(addr, txs[len(txs)-1].Nonce()+1)
 	}
 	// Check the queue and move transactions over to the pending if possible
 	// or remove those that have become invalid
-	pool.checkQueue()
+	pool.promoteExecutables()
 }
 
 func (pool *TxPool) Stop() {
 	pool.events.Unsubscribe()
+	close(pool.quit)
 	pool.wg.Wait()
 	glog.V(logger.Info).Infoln("Transaction pool stopped")
 }
@@ -170,47 +176,58 @@ func (pool *TxPool) State() *state.ManagedState {
 	return pool.pendingState
 }
 
+// Stats retrieves the current pool stats, namely the number of pending and the
+// number of queued (non-executable) transactions.
 func (pool *TxPool) Stats() (pending int, queued int) {
 	pool.mu.RLock()
 	defer pool.mu.RUnlock()
 
-	pending = len(pool.pending)
-	for _, txs := range pool.queue {
-		queued += len(txs)
+	for _, list := range pool.pending {
+		pending += list.Len()
+	}
+	for _, list := range pool.queue {
+		queued += list.Len()
 	}
 	return
 }
 
 // Content retrieves the data content of the transaction pool, returning all the
-// pending as well as queued transactions, grouped by account and nonce.
-func (pool *TxPool) Content() (map[common.Address]map[uint64][]*types.Transaction, map[common.Address]map[uint64][]*types.Transaction) {
+// pending as well as queued transactions, grouped by account and sorted by nonce.
+func (pool *TxPool) Content() (map[common.Address]types.Transactions, map[common.Address]types.Transactions) {
 	pool.mu.RLock()
 	defer pool.mu.RUnlock()
 
-	// Retrieve all the pending transactions and sort by account and by nonce
-	pending := make(map[common.Address]map[uint64][]*types.Transaction)
-	for _, tx := range pool.pending {
-		account, _ := tx.From()
-
-		owned, ok := pending[account]
-		if !ok {
-			owned = make(map[uint64][]*types.Transaction)
-			pending[account] = owned
-		}
-		owned[tx.Nonce()] = append(owned[tx.Nonce()], tx)
-	}
-	// Retrieve all the queued transactions and sort by account and by nonce
-	queued := make(map[common.Address]map[uint64][]*types.Transaction)
-	for account, txs := range pool.queue {
-		owned := make(map[uint64][]*types.Transaction)
-		for _, tx := range txs {
-			owned[tx.Nonce()] = append(owned[tx.Nonce()], tx)
-		}
-		queued[account] = owned
+	pending := make(map[common.Address]types.Transactions)
+	for addr, list := range pool.pending {
+		pending[addr] = list.Flatten()
+	}
+	queued := make(map[common.Address]types.Transactions)
+	for addr, list := range pool.queue {
+		queued[addr] = list.Flatten()
 	}
 	return pending, queued
 }
 
+// Pending retrieves all currently processable transactions, groupped by origin
+// account and sorted by nonce. The returned transaction set is a copy and can be
+// freely modified by calling code.
+func (pool *TxPool) Pending() map[common.Address]types.Transactions {
+	pool.mu.Lock()
+	defer pool.mu.Unlock()
+
+	// check queue first
+	pool.promoteExecutables()
+
+	// invalidate any txs
+	pool.demoteUnexecutables()
+
+	pending := make(map[common.Address]types.Transactions)
+	for addr, list := range pool.pending {
+		pending[addr] = list.Flatten()
+	}
+	return pending
+}
+
 // SetLocal marks a transaction as local, skipping gas price
 //  check against local miner minimum in the future
 func (pool *TxPool) SetLocal(tx *types.Transaction) {
@@ -276,312 +293,348 @@ func (pool *TxPool) validateTx(tx *types.Transaction) error {
 	return nil
 }
 
-// validate and queue transactions.
-func (self *TxPool) add(tx *types.Transaction) error {
+// add validates a transaction and inserts it into the non-executable queue for
+// later pending promotion and execution.
+func (pool *TxPool) add(tx *types.Transaction) error {
+	// If the transaction is alreayd known, discard it
 	hash := tx.Hash()
-
-	if self.pending[hash] != nil {
-		return fmt.Errorf("Known transaction (%x)", hash[:4])
+	if pool.all[hash] != nil {
+		return fmt.Errorf("Known transaction: %x", hash[:4])
 	}
-	err := self.validateTx(tx)
-	if err != nil {
+	// Otherwise ensure basic validation passes and queue it up
+	if err := pool.validateTx(tx); err != nil {
 		return err
 	}
-	self.queueTx(hash, tx)
+	pool.enqueueTx(hash, tx)
 
+	// Print a log message if low enough level is set
 	if glog.V(logger.Debug) {
-		var toname string
+		rcpt := "[NEW_CONTRACT]"
 		if to := tx.To(); to != nil {
-			toname = common.Bytes2Hex(to[:4])
-		} else {
-			toname = "[NEW_CONTRACT]"
+			rcpt = common.Bytes2Hex(to[:4])
 		}
-		// we can ignore the error here because From is
-		// verified in ValidateTransaction.
-		f, _ := tx.From()
-		from := common.Bytes2Hex(f[:4])
-		glog.Infof("(t) %x => %s (%v) %x\n", from, toname, tx.Value, hash)
+		from, _ := tx.From() // from already verified during tx validation
+		glog.Infof("(t) 0x%x => %s (%v) %x\n", from[:4], rcpt, tx.Value, hash)
 	}
-
 	return nil
 }
 
-// queueTx will queue an unknown transaction
-func (self *TxPool) queueTx(hash common.Hash, tx *types.Transaction) {
+// enqueueTx inserts a new transaction into the non-executable transaction queue.
+//
+// Note, this method assumes the pool lock is held!
+func (pool *TxPool) enqueueTx(hash common.Hash, tx *types.Transaction) {
+	// Try to insert the transaction into the future queue
 	from, _ := tx.From() // already validated
-	if self.queue[from] == nil {
-		self.queue[from] = make(map[common.Hash]*types.Transaction)
+	if pool.queue[from] == nil {
+		pool.queue[from] = newTxList(false)
+	}
+	inserted, old := pool.queue[from].Add(tx)
+	if !inserted {
+		return // An older transaction was better, discard this
+	}
+	// Discard any previous transaction and mark this
+	if old != nil {
+		delete(pool.all, old.Hash())
 	}
-	self.queue[from][hash] = tx
+	pool.all[hash] = tx
 }
 
-// addTx will add a transaction to the pending (processable queue) list of transactions
-func (pool *TxPool) addTx(hash common.Hash, addr common.Address, tx *types.Transaction) {
-	// init delayed since tx pool could have been started before any state sync
+// promoteTx adds a transaction to the pending (processable) list of transactions.
+//
+// Note, this method assumes the pool lock is held!
+func (pool *TxPool) promoteTx(addr common.Address, hash common.Hash, tx *types.Transaction) {
+	// Init delayed since tx pool could have been started before any state sync
 	if pool.pendingState == nil {
 		pool.resetState()
 	}
+	// Try to insert the transaction into the pending queue
+	if pool.pending[addr] == nil {
+		pool.pending[addr] = newTxList(true)
+	}
+	list := pool.pending[addr]
 
-	if _, ok := pool.pending[hash]; !ok {
-		pool.pending[hash] = tx
-
-		// Increment the nonce on the pending state. This can only happen if
-		// the nonce is +1 to the previous one.
-		pool.pendingState.SetNonce(addr, tx.Nonce()+1)
-		// Notify the subscribers. This event is posted in a goroutine
-		// because it's possible that somewhere during the post "Remove transaction"
-		// gets called which will then wait for the global tx pool lock and deadlock.
-		go pool.eventMux.Post(TxPreEvent{tx})
+	inserted, old := list.Add(tx)
+	if !inserted {
+		// An older transaction was better, discard this
+		delete(pool.all, hash)
+		return
+	}
+	// Otherwise discard any previous transaction and mark this
+	if old != nil {
+		delete(pool.all, old.Hash())
 	}
+	pool.all[hash] = tx // Failsafe to work around direct pending inserts (tests)
+
+	// Set the potentially new pending nonce and notify any subsystems of the new tx
+	pool.beats[addr] = time.Now()
+	pool.pendingState.SetNonce(addr, tx.Nonce()+1)
+	go pool.eventMux.Post(TxPreEvent{tx})
 }
 
 // Add queues a single transaction in the pool if it is valid.
-func (self *TxPool) Add(tx *types.Transaction) error {
-	self.mu.Lock()
-	defer self.mu.Unlock()
+func (pool *TxPool) Add(tx *types.Transaction) error {
+	pool.mu.Lock()
+	defer pool.mu.Unlock()
 
-	if err := self.add(tx); err != nil {
+	if err := pool.add(tx); err != nil {
 		return err
 	}
-	self.checkQueue()
+	pool.promoteExecutables()
+
 	return nil
 }
 
-// AddTransactions attempts to queue all valid transactions in txs.
-func (self *TxPool) AddTransactions(txs []*types.Transaction) {
-	self.mu.Lock()
-	defer self.mu.Unlock()
+// AddBatch attempts to queue a batch of transactions.
+func (pool *TxPool) AddBatch(txs []*types.Transaction) {
+	pool.mu.Lock()
+	defer pool.mu.Unlock()
 
 	for _, tx := range txs {
-		if err := self.add(tx); err != nil {
+		if err := pool.add(tx); err != nil {
 			glog.V(logger.Debug).Infoln("tx error:", err)
-		} else {
-			h := tx.Hash()
-			glog.V(logger.Debug).Infof("tx %x\n", h[:4])
 		}
 	}
-
-	// check and validate the queue
-	self.checkQueue()
+	pool.promoteExecutables()
 }
 
-// GetTransaction returns a transaction if it is contained in the pool
+// Get returns a transaction if it is contained in the pool
 // and nil otherwise.
-func (tp *TxPool) GetTransaction(hash common.Hash) *types.Transaction {
-	tp.mu.RLock()
-	defer tp.mu.RUnlock()
-
-	// check the txs first
-	if tx, ok := tp.pending[hash]; ok {
-		return tx
-	}
-	// check queue
-	for _, txs := range tp.queue {
-		if tx, ok := txs[hash]; ok {
-			return tx
-		}
-	}
-	return nil
-}
+func (pool *TxPool) Get(hash common.Hash) *types.Transaction {
+	pool.mu.RLock()
+	defer pool.mu.RUnlock()
 
-// GetTransactions returns all currently processable transactions.
-// The returned slice may be modified by the caller.
-func (self *TxPool) GetTransactions() (txs types.Transactions) {
-	self.mu.Lock()
-	defer self.mu.Unlock()
+	return pool.all[hash]
+}
 
-	// check queue first
-	self.checkQueue()
-	// invalidate any txs
-	self.validatePool()
+// Remove removes the transaction with the given hash from the pool.
+func (pool *TxPool) Remove(hash common.Hash) {
+	pool.mu.Lock()
+	defer pool.mu.Unlock()
 
-	txs = make(types.Transactions, len(self.pending))
-	i := 0
-	for _, tx := range self.pending {
-		txs[i] = tx
-		i++
-	}
-	return txs
+	pool.removeTx(hash)
 }
 
-// GetQueuedTransactions returns all non-processable transactions.
-func (self *TxPool) GetQueuedTransactions() types.Transactions {
-	self.mu.RLock()
-	defer self.mu.RUnlock()
+// RemoveBatch removes all given transactions from the pool.
+func (pool *TxPool) RemoveBatch(txs types.Transactions) {
+	pool.mu.Lock()
+	defer pool.mu.Unlock()
 
-	var ret types.Transactions
-	for _, txs := range self.queue {
-		for _, tx := range txs {
-			ret = append(ret, tx)
-		}
+	for _, tx := range txs {
+		pool.removeTx(tx.Hash())
 	}
-	sort.Sort(types.TxByNonce(ret))
-	return ret
 }
 
-// RemoveTransactions removes all given transactions from the pool.
-func (self *TxPool) RemoveTransactions(txs types.Transactions) {
-	self.mu.Lock()
-	defer self.mu.Unlock()
-	for _, tx := range txs {
-		self.removeTx(tx.Hash())
+// removeTx removes a single transaction from the queue, moving all subsequent
+// transactions back to the future queue.
+func (pool *TxPool) removeTx(hash common.Hash) {
+	// Fetch the transaction we wish to delete
+	tx, ok := pool.all[hash]
+	if !ok {
+		return
 	}
-}
+	addr, _ := tx.From() // already validated during insertion
 
-// RemoveTx removes the transaction with the given hash from the pool.
-func (pool *TxPool) RemoveTx(hash common.Hash) {
-	pool.mu.Lock()
-	defer pool.mu.Unlock()
-	pool.removeTx(hash)
-}
+	// Remove it from the list of known transactions
+	delete(pool.all, hash)
 
-func (pool *TxPool) removeTx(hash common.Hash) {
-	// delete from pending pool
-	delete(pool.pending, hash)
-	// delete from queue
-	for address, txs := range pool.queue {
-		if _, ok := txs[hash]; ok {
-			if len(txs) == 1 {
-				// if only one tx, remove entire address entry.
-				delete(pool.queue, address)
+	// Remove the transaction from the pending lists and reset the account nonce
+	if pending := pool.pending[addr]; pending != nil {
+		if removed, invalids := pending.Remove(tx); removed {
+			// If no more transactions are left, remove the list
+			if pending.Empty() {
+				delete(pool.pending, addr)
+				delete(pool.beats, addr)
 			} else {
-				delete(txs, hash)
+				// Otherwise postpone any invalidated transactions
+				for _, tx := range invalids {
+					pool.enqueueTx(tx.Hash(), tx)
+				}
+			}
+			// Update the account nonce if needed
+			if nonce := tx.Nonce(); pool.pendingState.GetNonce(addr) > nonce {
+				pool.pendingState.SetNonce(addr, tx.Nonce())
 			}
-			break
+		}
+	}
+	// Transaction is in the future queue
+	if future := pool.queue[addr]; future != nil {
+		future.Remove(tx)
+		if future.Empty() {
+			delete(pool.queue, addr)
 		}
 	}
 }
 
-// checkQueue moves transactions that have become processable to main pool.
-func (pool *TxPool) checkQueue() {
-	// init delayed since tx pool could have been started before any state sync
+// promoteExecutables moves transactions that have become processable from the
+// future queue to the set of pending transactions. During this process, all
+// invalidated transactions (low nonce, low balance) are deleted.
+func (pool *TxPool) promoteExecutables() {
+	// Init delayed since tx pool could have been started before any state sync
 	if pool.pendingState == nil {
 		pool.resetState()
 	}
+	// Retrieve the current state to allow nonce and balance checking
+	state, err := pool.currentState()
+	if err != nil {
+		glog.Errorf("Could not get current state: %v", err)
+		return
+	}
+	// Iterate over all accounts and promote any executable transactions
+	queued := uint64(0)
 
-	var promote txQueue
-	for address, txs := range pool.queue {
-		currentState, err := pool.currentState()
-		if err != nil {
-			glog.Errorf("could not get current state: %v", err)
-			return
+	for addr, list := range pool.queue {
+		// Drop all transactions that are deemed too old (low nonce)
+		for _, tx := range list.Forward(state.GetNonce(addr)) {
+			if glog.V(logger.Core) {
+				glog.Infof("Removed old queued transaction: %v", tx)
+			}
+			delete(pool.all, tx.Hash())
 		}
-		balance := currentState.GetBalance(address)
-
-		var (
-			guessedNonce = pool.pendingState.GetNonce(address) // nonce currently kept by the tx pool (pending state)
-			trueNonce    = currentState.GetNonce(address)      // nonce known by the last state
-		)
-		promote = promote[:0]
-		for hash, tx := range txs {
-			// Drop processed or out of fund transactions
-			if tx.Nonce() < trueNonce || balance.Cmp(tx.Cost()) < 0 {
-				if glog.V(logger.Core) {
-					glog.Infof("removed tx (%v) from pool queue: low tx nonce or out of funds\n", tx)
-				}
-				delete(txs, hash)
-				continue
+		// Drop all transactions that are too costly (low balance)
+		drops, _ := list.Filter(state.GetBalance(addr))
+		for _, tx := range drops {
+			if glog.V(logger.Core) {
+				glog.Infof("Removed unpayable queued transaction: %v", tx)
 			}
-			// Collect the remaining transactions for the next pass.
-			promote = append(promote, txQueueEntry{hash, address, tx})
+			delete(pool.all, tx.Hash())
 		}
-		// Find the next consecutive nonce range starting at the current account nonce,
-		// pushing the guessed nonce forward if we add consecutive transactions.
-		sort.Sort(promote)
-		for i, entry := range promote {
-			// If we reached a gap in the nonces, enforce transaction limit and stop
-			if entry.Nonce() > guessedNonce {
-				if len(promote)-i > maxQueued {
-					if glog.V(logger.Debug) {
-						glog.Infof("Queued tx limit exceeded for %s. Tx %s removed\n", common.PP(address[:]), common.PP(entry.hash[:]))
-					}
-					for _, drop := range promote[i+maxQueued:] {
-						delete(txs, drop.hash)
-					}
-				}
-				break
+		// Gather all executable transactions and promote them
+		for _, tx := range list.Ready(pool.pendingState.GetNonce(addr)) {
+			if glog.V(logger.Core) {
+				glog.Infof("Promoting queued transaction: %v", tx)
 			}
-			// Otherwise promote the transaction and move the guess nonce if needed
-			pool.addTx(entry.hash, address, entry.Transaction)
-			delete(txs, entry.hash)
-
-			if entry.Nonce() == guessedNonce {
-				guessedNonce++
+			pool.promoteTx(addr, tx.Hash(), tx)
+		}
+		// Drop all transactions over the allowed limit
+		for _, tx := range list.Cap(int(maxQueuedPerAccount)) {
+			if glog.V(logger.Core) {
+				glog.Infof("Removed cap-exceeding queued transaction: %v", tx)
 			}
+			delete(pool.all, tx.Hash())
 		}
+		queued += uint64(list.Len())
+
 		// Delete the entire queue entry if it became empty.
-		if len(txs) == 0 {
-			delete(pool.queue, address)
+		if list.Empty() {
+			delete(pool.queue, addr)
+		}
+	}
+	// If we've queued more transactions than the hard limit, drop oldest ones
+	if queued > maxQueuedInTotal {
+		// Sort all accounts with queued transactions by heartbeat
+		addresses := make(addresssByHeartbeat, 0, len(pool.queue))
+		for addr, _ := range pool.queue {
+			addresses = append(addresses, addressByHeartbeat{addr, pool.beats[addr]})
+		}
+		sort.Sort(addresses)
+
+		// Drop transactions until the total is below the limit
+		for drop := queued - maxQueuedInTotal; drop > 0; {
+			addr := addresses[len(addresses)-1]
+			list := pool.queue[addr.address]
+
+			addresses = addresses[:len(addresses)-1]
+
+			// Drop all transactions if they are less than the overflow
+			if size := uint64(list.Len()); size <= drop {
+				for _, tx := range list.Flatten() {
+					pool.removeTx(tx.Hash())
+				}
+				drop -= size
+				continue
+			}
+			// Otherwise drop only last few transactions
+			txs := list.Flatten()
+			for i := len(txs) - 1; i >= 0 && drop > 0; i-- {
+				pool.removeTx(txs[i].Hash())
+				drop--
+			}
 		}
 	}
 }
 
-// validatePool removes invalid and processed transactions from the main pool.
-// If a transaction is removed for being invalid (e.g. out of funds), all sub-
-// sequent (Still valid) transactions are moved back into the future queue. This
-// is important to prevent a drained account from DOSing the network with non
-// executable transactions.
-func (pool *TxPool) validatePool() {
+// demoteUnexecutables removes invalid and processed transactions from the pools
+// executable/pending queue and any subsequent transactions that become unexecutable
+// are moved back into the future queue.
+func (pool *TxPool) demoteUnexecutables() {
+	// Retrieve the current state to allow nonce and balance checking
 	state, err := pool.currentState()
 	if err != nil {
 		glog.V(logger.Info).Infoln("failed to get current state: %v", err)
 		return
 	}
-	balanceCache := make(map[common.Address]*big.Int)
-
-	// Clean up the pending pool, accumulating invalid nonces
-	gaps := make(map[common.Address]uint64)
+	// Iterate over all accounts and demote any non-executable transactions
+	for addr, list := range pool.pending {
+		nonce := state.GetNonce(addr)
 
-	for hash, tx := range pool.pending {
-		sender, _ := tx.From() // err already checked
-
-		// Perform light nonce and balance validation
-		balance := balanceCache[sender]
-		if balance == nil {
-			balance = state.GetBalance(sender)
-			balanceCache[sender] = balance
+		// Drop all transactions that are deemed too old (low nonce)
+		for _, tx := range list.Forward(nonce) {
+			if glog.V(logger.Core) {
+				glog.Infof("Removed old pending transaction: %v", tx)
+			}
+			delete(pool.all, tx.Hash())
 		}
-		if past := state.GetNonce(sender) > tx.Nonce(); past || balance.Cmp(tx.Cost()) < 0 {
-			// Remove an already past it invalidated transaction
+		// Drop all transactions that are too costly (low balance), and queue any invalids back for later
+		drops, invalids := list.Filter(state.GetBalance(addr))
+		for _, tx := range drops {
 			if glog.V(logger.Core) {
-				glog.Infof("removed tx (%v) from pool: low tx nonce or out of funds\n", tx)
+				glog.Infof("Removed unpayable pending transaction: %v", tx)
 			}
-			delete(pool.pending, hash)
-
-			// Track the smallest invalid nonce to postpone subsequent transactions
-			if !past {
-				if prev, ok := gaps[sender]; !ok || tx.Nonce() < prev {
-					gaps[sender] = tx.Nonce()
-				}
+			delete(pool.all, tx.Hash())
+		}
+		for _, tx := range invalids {
+			if glog.V(logger.Core) {
+				glog.Infof("Demoting pending transaction: %v", tx)
 			}
+			pool.enqueueTx(tx.Hash(), tx)
+		}
+		// Delete the entire queue entry if it became empty.
+		if list.Empty() {
+			delete(pool.pending, addr)
+			delete(pool.beats, addr)
 		}
 	}
-	// Move all transactions after a gap back to the future queue
-	if len(gaps) > 0 {
-		for hash, tx := range pool.pending {
-			sender, _ := tx.From()
-			if gap, ok := gaps[sender]; ok && tx.Nonce() >= gap {
-				if glog.V(logger.Core) {
-					glog.Infof("postponed tx (%v) due to introduced gap\n", tx)
+}
+
+// expirationLoop is a loop that periodically iterates over all accounts with
+// queued transactions and drop all that have been inactive for a prolonged amount
+// of time.
+func (pool *TxPool) expirationLoop() {
+	defer pool.wg.Done()
+
+	evict := time.NewTicker(evictionInterval)
+	defer evict.Stop()
+
+	for {
+		select {
+		case <-evict.C:
+			pool.mu.Lock()
+			for addr := range pool.queue {
+				if time.Since(pool.beats[addr]) > maxQueuedLifetime {
+					for _, tx := range pool.queue[addr].Flatten() {
+						pool.removeTx(tx.Hash())
+					}
 				}
-				pool.queueTx(hash, tx)
-				delete(pool.pending, hash)
 			}
+			pool.mu.Unlock()
+
+		case <-pool.quit:
+			return
 		}
 	}
 }
 
-type txQueue []txQueueEntry
-
-type txQueueEntry struct {
-	hash common.Hash
-	addr common.Address
-	*types.Transaction
+// addressByHeartbeat is an account address tagged with its last activity timestamp.
+type addressByHeartbeat struct {
+	address   common.Address
+	heartbeat time.Time
 }
 
-func (q txQueue) Len() int           { return len(q) }
-func (q txQueue) Swap(i, j int)      { q[i], q[j] = q[j], q[i] }
-func (q txQueue) Less(i, j int) bool { return q[i].Nonce() < q[j].Nonce() }
+type addresssByHeartbeat []addressByHeartbeat
+
+func (a addresssByHeartbeat) Len() int           { return len(a) }
+func (a addresssByHeartbeat) Less(i, j int) bool { return a[i].heartbeat.Before(a[j].heartbeat) }
+func (a addresssByHeartbeat) Swap(i, j int)      { a[i], a[j] = a[j], a[i] }
 
 // txSet represents a set of transaction hashes in which entries
 //  are automatically dropped after txSetDuration time
diff --git a/core/tx_pool_test.go b/core/tx_pool_test.go
index ed9bea75f..4bc5aed38 100644
--- a/core/tx_pool_test.go
+++ b/core/tx_pool_test.go
@@ -19,7 +19,9 @@ package core
 import (
 	"crypto/ecdsa"
 	"math/big"
+	"math/rand"
 	"testing"
+	"time"
 
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/core/state"
@@ -38,10 +40,10 @@ func setupTxPool() (*TxPool, *ecdsa.PrivateKey) {
 	db, _ := ethdb.NewMemDatabase()
 	statedb, _ := state.New(common.Hash{}, db)
 
-	var m event.TypeMux
 	key, _ := crypto.GenerateKey()
-	newPool := NewTxPool(testChainConfig(), &m, func() (*state.StateDB, error) { return statedb, nil }, func() *big.Int { return big.NewInt(1000000) })
+	newPool := NewTxPool(testChainConfig(), new(event.TypeMux), func() (*state.StateDB, error) { return statedb, nil }, func() *big.Int { return big.NewInt(1000000) })
 	newPool.resetState()
+
 	return newPool, key
 }
 
@@ -91,9 +93,9 @@ func TestTransactionQueue(t *testing.T) {
 	from, _ := tx.From()
 	currentState, _ := pool.currentState()
 	currentState.AddBalance(from, big.NewInt(1000))
-	pool.queueTx(tx.Hash(), tx)
+	pool.enqueueTx(tx.Hash(), tx)
 
-	pool.checkQueue()
+	pool.promoteExecutables()
 	if len(pool.pending) != 1 {
 		t.Error("expected valid txs to be 1 is", len(pool.pending))
 	}
@@ -101,14 +103,14 @@ func TestTransactionQueue(t *testing.T) {
 	tx = transaction(1, big.NewInt(100), key)
 	from, _ = tx.From()
 	currentState.SetNonce(from, 2)
-	pool.queueTx(tx.Hash(), tx)
-	pool.checkQueue()
-	if _, ok := pool.pending[tx.Hash()]; ok {
+	pool.enqueueTx(tx.Hash(), tx)
+	pool.promoteExecutables()
+	if _, ok := pool.pending[from].txs.items[tx.Nonce()]; ok {
 		t.Error("expected transaction to be in tx pool")
 	}
 
-	if len(pool.queue[from]) > 0 {
-		t.Error("expected transaction queue to be empty. is", len(pool.queue[from]))
+	if len(pool.queue) > 0 {
+		t.Error("expected transaction queue to be empty. is", len(pool.queue))
 	}
 
 	pool, key = setupTxPool()
@@ -118,17 +120,17 @@ func TestTransactionQueue(t *testing.T) {
 	from, _ = tx1.From()
 	currentState, _ = pool.currentState()
 	currentState.AddBalance(from, big.NewInt(1000))
-	pool.queueTx(tx1.Hash(), tx1)
-	pool.queueTx(tx2.Hash(), tx2)
-	pool.queueTx(tx3.Hash(), tx3)
+	pool.enqueueTx(tx1.Hash(), tx1)
+	pool.enqueueTx(tx2.Hash(), tx2)
+	pool.enqueueTx(tx3.Hash(), tx3)
 
-	pool.checkQueue()
+	pool.promoteExecutables()
 
 	if len(pool.pending) != 1 {
 		t.Error("expected tx pool to be 1, got", len(pool.pending))
 	}
-	if len(pool.queue[from]) != 2 {
-		t.Error("expected len(queue) == 2, got", len(pool.queue[from]))
+	if pool.queue[from].Len() != 2 {
+		t.Error("expected len(queue) == 2, got", pool.queue[from].Len())
 	}
 }
 
@@ -138,24 +140,21 @@ func TestRemoveTx(t *testing.T) {
 	from, _ := tx.From()
 	currentState, _ := pool.currentState()
 	currentState.AddBalance(from, big.NewInt(1))
-	pool.queueTx(tx.Hash(), tx)
-	pool.addTx(tx.Hash(), from, tx)
+
+	pool.enqueueTx(tx.Hash(), tx)
+	pool.promoteTx(from, tx.Hash(), tx)
 	if len(pool.queue) != 1 {
 		t.Error("expected queue to be 1, got", len(pool.queue))
 	}
-
 	if len(pool.pending) != 1 {
-		t.Error("expected txs to be 1, got", len(pool.pending))
+		t.Error("expected pending to be 1, got", len(pool.pending))
 	}
-
-	pool.RemoveTx(tx.Hash())
-
+	pool.Remove(tx.Hash())
 	if len(pool.queue) > 0 {
 		t.Error("expected queue to be 0, got", len(pool.queue))
 	}
-
 	if len(pool.pending) > 0 {
-		t.Error("expected txs to be 0, got", len(pool.pending))
+		t.Error("expected pending to be 0, got", len(pool.pending))
 	}
 }
 
@@ -188,7 +187,7 @@ func TestTransactionChainFork(t *testing.T) {
 	if err := pool.add(tx); err != nil {
 		t.Error("didn't expect error", err)
 	}
-	pool.RemoveTransactions([]*types.Transaction{tx})
+	pool.RemoveBatch([]*types.Transaction{tx})
 
 	// reset the pool's internal state
 	resetState()
@@ -210,18 +209,38 @@ func TestTransactionDoubleNonce(t *testing.T) {
 	}
 	resetState()
 
-	tx := transaction(0, big.NewInt(100000), key)
-	tx2 := transaction(0, big.NewInt(1000000), key)
-	if err := pool.add(tx); err != nil {
+	tx1, _ := types.NewTransaction(0, common.Address{}, big.NewInt(100), big.NewInt(100000), big.NewInt(1), nil).SignECDSA(key)
+	tx2, _ := types.NewTransaction(0, common.Address{}, big.NewInt(100), big.NewInt(1000000), big.NewInt(2), nil).SignECDSA(key)
+	tx3, _ := types.NewTransaction(0, common.Address{}, big.NewInt(100), big.NewInt(1000000), big.NewInt(1), nil).SignECDSA(key)
+
+	// Add the first two transaction, ensure higher priced stays only
+	if err := pool.add(tx1); err != nil {
 		t.Error("didn't expect error", err)
 	}
 	if err := pool.add(tx2); err != nil {
 		t.Error("didn't expect error", err)
 	}
-
-	pool.checkQueue()
-	if len(pool.pending) != 2 {
-		t.Error("expected 2 pending txs. Got", len(pool.pending))
+	pool.promoteExecutables()
+	if pool.pending[addr].Len() != 1 {
+		t.Error("expected 1 pending transactions, got", pool.pending[addr].Len())
+	}
+	if tx := pool.pending[addr].txs.items[0]; tx.Hash() != tx2.Hash() {
+		t.Errorf("transaction mismatch: have %x, want %x", tx.Hash(), tx2.Hash())
+	}
+	// Add the thid transaction and ensure it's not saved (smaller price)
+	if err := pool.add(tx3); err != nil {
+		t.Error("didn't expect error", err)
+	}
+	pool.promoteExecutables()
+	if pool.pending[addr].Len() != 1 {
+		t.Error("expected 1 pending transactions, got", pool.pending[addr].Len())
+	}
+	if tx := pool.pending[addr].txs.items[0]; tx.Hash() != tx2.Hash() {
+		t.Errorf("transaction mismatch: have %x, want %x", tx.Hash(), tx2.Hash())
+	}
+	// Ensure the total transaction count is correct
+	if len(pool.all) != 1 {
+		t.Error("expected 1 total transactions, got", len(pool.all))
 	}
 }
 
@@ -237,8 +256,11 @@ func TestMissingNonce(t *testing.T) {
 	if len(pool.pending) != 0 {
 		t.Error("expected 0 pending transactions, got", len(pool.pending))
 	}
-	if len(pool.queue[addr]) != 1 {
-		t.Error("expected 1 queued transaction, got", len(pool.queue[addr]))
+	if pool.queue[addr].Len() != 1 {
+		t.Error("expected 1 queued transaction, got", pool.queue[addr].Len())
+	}
+	if len(pool.all) != 1 {
+		t.Error("expected 1 total transactions, got", len(pool.all))
 	}
 }
 
@@ -270,8 +292,11 @@ func TestRemovedTxEvent(t *testing.T) {
 	currentState.AddBalance(from, big.NewInt(1000000000000))
 	pool.eventMux.Post(RemovedTransactionEvent{types.Transactions{tx}})
 	pool.eventMux.Post(ChainHeadEvent{nil})
-	if len(pool.pending) != 1 {
-		t.Error("expected 1 pending tx, got", len(pool.pending))
+	if pool.pending[from].Len() != 1 {
+		t.Error("expected 1 pending tx, got", pool.pending[from].Len())
+	}
+	if len(pool.all) != 1 {
+		t.Error("expected 1 total transactions, got", len(pool.all))
 	}
 }
 
@@ -292,41 +317,50 @@ func TestTransactionDropping(t *testing.T) {
 		tx10 = transaction(10, big.NewInt(100), key)
 		tx11 = transaction(11, big.NewInt(200), key)
 	)
-	pool.addTx(tx0.Hash(), account, tx0)
-	pool.addTx(tx1.Hash(), account, tx1)
-	pool.queueTx(tx10.Hash(), tx10)
-	pool.queueTx(tx11.Hash(), tx11)
+	pool.promoteTx(account, tx0.Hash(), tx0)
+	pool.promoteTx(account, tx1.Hash(), tx1)
+	pool.enqueueTx(tx10.Hash(), tx10)
+	pool.enqueueTx(tx11.Hash(), tx11)
 
 	// Check that pre and post validations leave the pool as is
-	if len(pool.pending) != 2 {
-		t.Errorf("pending transaction mismatch: have %d, want %d", len(pool.pending), 2)
+	if pool.pending[account].Len() != 2 {
+		t.Errorf("pending transaction mismatch: have %d, want %d", pool.pending[account].Len(), 2)
 	}
-	if len(pool.queue[account]) != 2 {
-		t.Errorf("queued transaction mismatch: have %d, want %d", len(pool.queue), 2)
+	if pool.queue[account].Len() != 2 {
+		t.Errorf("queued transaction mismatch: have %d, want %d", pool.queue[account].Len(), 2)
+	}
+	if len(pool.all) != 4 {
+		t.Errorf("total transaction mismatch: have %d, want %d", len(pool.all), 4)
 	}
 	pool.resetState()
-	if len(pool.pending) != 2 {
-		t.Errorf("pending transaction mismatch: have %d, want %d", len(pool.pending), 2)
+	if pool.pending[account].Len() != 2 {
+		t.Errorf("pending transaction mismatch: have %d, want %d", pool.pending[account].Len(), 2)
+	}
+	if pool.queue[account].Len() != 2 {
+		t.Errorf("queued transaction mismatch: have %d, want %d", pool.queue[account].Len(), 2)
 	}
-	if len(pool.queue[account]) != 2 {
-		t.Errorf("queued transaction mismatch: have %d, want %d", len(pool.queue), 2)
+	if len(pool.all) != 4 {
+		t.Errorf("total transaction mismatch: have %d, want %d", len(pool.all), 4)
 	}
 	// Reduce the balance of the account, and check that invalidated transactions are dropped
 	state.AddBalance(account, big.NewInt(-750))
 	pool.resetState()
 
-	if _, ok := pool.pending[tx0.Hash()]; !ok {
+	if _, ok := pool.pending[account].txs.items[tx0.Nonce()]; !ok {
 		t.Errorf("funded pending transaction missing: %v", tx0)
 	}
-	if _, ok := pool.pending[tx1.Hash()]; ok {
+	if _, ok := pool.pending[account].txs.items[tx1.Nonce()]; ok {
 		t.Errorf("out-of-fund pending transaction present: %v", tx1)
 	}
-	if _, ok := pool.queue[account][tx10.Hash()]; !ok {
+	if _, ok := pool.queue[account].txs.items[tx10.Nonce()]; !ok {
 		t.Errorf("funded queued transaction missing: %v", tx10)
 	}
-	if _, ok := pool.queue[account][tx11.Hash()]; ok {
+	if _, ok := pool.queue[account].txs.items[tx11.Nonce()]; ok {
 		t.Errorf("out-of-fund queued transaction present: %v", tx11)
 	}
+	if len(pool.all) != 2 {
+		t.Errorf("total transaction mismatch: have %d, want %d", len(pool.all), 2)
+	}
 }
 
 // Tests that if a transaction is dropped from the current pending pool (e.g. out
@@ -349,55 +383,64 @@ func TestTransactionPostponing(t *testing.T) {
 		} else {
 			tx = transaction(uint64(i), big.NewInt(500), key)
 		}
-		pool.addTx(tx.Hash(), account, tx)
+		pool.promoteTx(account, tx.Hash(), tx)
 		txns = append(txns, tx)
 	}
 	// Check that pre and post validations leave the pool as is
-	if len(pool.pending) != len(txns) {
-		t.Errorf("pending transaction mismatch: have %d, want %d", len(pool.pending), len(txns))
+	if pool.pending[account].Len() != len(txns) {
+		t.Errorf("pending transaction mismatch: have %d, want %d", pool.pending[account].Len(), len(txns))
+	}
+	if len(pool.queue) != 0 {
+		t.Errorf("queued transaction mismatch: have %d, want %d", pool.queue[account].Len(), 0)
 	}
-	if len(pool.queue[account]) != 0 {
-		t.Errorf("queued transaction mismatch: have %d, want %d", len(pool.queue), 0)
+	if len(pool.all) != len(txns) {
+		t.Errorf("total transaction mismatch: have %d, want %d", len(pool.all), len(txns))
 	}
 	pool.resetState()
-	if len(pool.pending) != len(txns) {
-		t.Errorf("pending transaction mismatch: have %d, want %d", len(pool.pending), len(txns))
+	if pool.pending[account].Len() != len(txns) {
+		t.Errorf("pending transaction mismatch: have %d, want %d", pool.pending[account].Len(), len(txns))
+	}
+	if len(pool.queue) != 0 {
+		t.Errorf("queued transaction mismatch: have %d, want %d", pool.queue[account].Len(), 0)
 	}
-	if len(pool.queue[account]) != 0 {
-		t.Errorf("queued transaction mismatch: have %d, want %d", len(pool.queue), 0)
+	if len(pool.all) != len(txns) {
+		t.Errorf("total transaction mismatch: have %d, want %d", len(pool.all), len(txns))
 	}
 	// Reduce the balance of the account, and check that transactions are reorganised
 	state.AddBalance(account, big.NewInt(-750))
 	pool.resetState()
 
-	if _, ok := pool.pending[txns[0].Hash()]; !ok {
+	if _, ok := pool.pending[account].txs.items[txns[0].Nonce()]; !ok {
 		t.Errorf("tx %d: valid and funded transaction missing from pending pool: %v", 0, txns[0])
 	}
-	if _, ok := pool.queue[account][txns[0].Hash()]; ok {
+	if _, ok := pool.queue[account].txs.items[txns[0].Nonce()]; ok {
 		t.Errorf("tx %d: valid and funded transaction present in future queue: %v", 0, txns[0])
 	}
 	for i, tx := range txns[1:] {
 		if i%2 == 1 {
-			if _, ok := pool.pending[tx.Hash()]; ok {
+			if _, ok := pool.pending[account].txs.items[tx.Nonce()]; ok {
 				t.Errorf("tx %d: valid but future transaction present in pending pool: %v", i+1, tx)
 			}
-			if _, ok := pool.queue[account][tx.Hash()]; !ok {
+			if _, ok := pool.queue[account].txs.items[tx.Nonce()]; !ok {
 				t.Errorf("tx %d: valid but future transaction missing from future queue: %v", i+1, tx)
 			}
 		} else {
-			if _, ok := pool.pending[tx.Hash()]; ok {
+			if _, ok := pool.pending[account].txs.items[tx.Nonce()]; ok {
 				t.Errorf("tx %d: out-of-fund transaction present in pending pool: %v", i+1, tx)
 			}
-			if _, ok := pool.queue[account][tx.Hash()]; ok {
+			if _, ok := pool.queue[account].txs.items[tx.Nonce()]; ok {
 				t.Errorf("tx %d: out-of-fund transaction present in future queue: %v", i+1, tx)
 			}
 		}
 	}
+	if len(pool.all) != len(txns)/2 {
+		t.Errorf("total transaction mismatch: have %d, want %d", len(pool.all), len(txns)/2)
+	}
 }
 
 // Tests that if the transaction count belonging to a single account goes above
 // some threshold, the higher transactions are dropped to prevent DOS attacks.
-func TestTransactionQueueLimiting(t *testing.T) {
+func TestTransactionQueueAccountLimiting(t *testing.T) {
 	// Create a test account and fund it
 	pool, key := setupTxPool()
 	account, _ := transaction(0, big.NewInt(0), key).From()
@@ -406,23 +449,104 @@ func TestTransactionQueueLimiting(t *testing.T) {
 	state.AddBalance(account, big.NewInt(1000000))
 
 	// Keep queuing up transactions and make sure all above a limit are dropped
-	for i := uint64(1); i <= maxQueued+5; i++ {
+	for i := uint64(1); i <= maxQueuedPerAccount+5; i++ {
 		if err := pool.Add(transaction(i, big.NewInt(100000), key)); err != nil {
 			t.Fatalf("tx %d: failed to add transaction: %v", i, err)
 		}
 		if len(pool.pending) != 0 {
 			t.Errorf("tx %d: pending pool size mismatch: have %d, want %d", i, len(pool.pending), 0)
 		}
-		if i <= maxQueued {
-			if len(pool.queue[account]) != int(i) {
-				t.Errorf("tx %d: queue size mismatch: have %d, want %d", i, len(pool.queue[account]), i)
+		if i <= maxQueuedPerAccount {
+			if pool.queue[account].Len() != int(i) {
+				t.Errorf("tx %d: queue size mismatch: have %d, want %d", i, pool.queue[account].Len(), i)
 			}
 		} else {
-			if len(pool.queue[account]) != maxQueued {
-				t.Errorf("tx %d: queue limit mismatch: have %d, want %d", i, len(pool.queue[account]), maxQueued)
+			if pool.queue[account].Len() != int(maxQueuedPerAccount) {
+				t.Errorf("tx %d: queue limit mismatch: have %d, want %d", i, pool.queue[account].Len(), maxQueuedPerAccount)
 			}
 		}
 	}
+	if len(pool.all) != int(maxQueuedPerAccount) {
+		t.Errorf("total transaction mismatch: have %d, want %d", len(pool.all), maxQueuedPerAccount)
+	}
+}
+
+// Tests that if the transaction count belonging to multiple accounts go above
+// some threshold, the higher transactions are dropped to prevent DOS attacks.
+func TestTransactionQueueGlobalLimiting(t *testing.T) {
+	// Reduce the queue limits to shorten test time
+	defer func(old uint64) { maxQueuedInTotal = old }(maxQueuedInTotal)
+	maxQueuedInTotal = maxQueuedPerAccount * 3
+
+	// Create the pool to test the limit enforcement with
+	db, _ := ethdb.NewMemDatabase()
+	statedb, _ := state.New(common.Hash{}, db)
+
+	pool := NewTxPool(testChainConfig(), new(event.TypeMux), func() (*state.StateDB, error) { return statedb, nil }, func() *big.Int { return big.NewInt(1000000) })
+	pool.resetState()
+
+	// Create a number of test accounts and fund them
+	state, _ := pool.currentState()
+
+	keys := make([]*ecdsa.PrivateKey, 5)
+	for i := 0; i < len(keys); i++ {
+		keys[i], _ = crypto.GenerateKey()
+		state.AddBalance(crypto.PubkeyToAddress(keys[i].PublicKey), big.NewInt(1000000))
+	}
+	// Generate and queue a batch of transactions
+	nonces := make(map[common.Address]uint64)
+
+	txs := make(types.Transactions, 0, 3*maxQueuedInTotal)
+	for len(txs) < cap(txs) {
+		key := keys[rand.Intn(len(keys))]
+		addr := crypto.PubkeyToAddress(key.PublicKey)
+
+		txs = append(txs, transaction(nonces[addr]+1, big.NewInt(100000), key))
+		nonces[addr]++
+	}
+	// Import the batch and verify that limits have been enforced
+	pool.AddBatch(txs)
+
+	queued := 0
+	for addr, list := range pool.queue {
+		if list.Len() > int(maxQueuedPerAccount) {
+			t.Errorf("addr %x: queued accounts overflown allowance: %d > %d", addr, list.Len(), maxQueuedPerAccount)
+		}
+		queued += list.Len()
+	}
+	if queued > int(maxQueuedInTotal) {
+		t.Fatalf("total transactions overflow allowance: %d > %d", queued, maxQueuedInTotal)
+	}
+}
+
+// Tests that if an account remains idle for a prolonged amount of time, any
+// non-executable transactions queued up are dropped to prevent wasting resources
+// on shuffling them around.
+func TestTransactionQueueTimeLimiting(t *testing.T) {
+	// Reduce the queue limits to shorten test time
+	defer func(old time.Duration) { maxQueuedLifetime = old }(maxQueuedLifetime)
+	defer func(old time.Duration) { evictionInterval = old }(evictionInterval)
+	maxQueuedLifetime = time.Second
+	evictionInterval = time.Second
+
+	// Create a test account and fund it
+	pool, key := setupTxPool()
+	account, _ := transaction(0, big.NewInt(0), key).From()
+
+	state, _ := pool.currentState()
+	state.AddBalance(account, big.NewInt(1000000))
+
+	// Queue up a batch of transactions
+	for i := uint64(1); i <= maxQueuedPerAccount; i++ {
+		if err := pool.Add(transaction(i, big.NewInt(100000), key)); err != nil {
+			t.Fatalf("tx %d: failed to add transaction: %v", i, err)
+		}
+	}
+	// Wait until at least two expiration cycles hit and make sure the transactions are gone
+	time.Sleep(2 * evictionInterval)
+	if len(pool.queue) > 0 {
+		t.Fatalf("old transactions remained after eviction")
+	}
 }
 
 // Tests that even if the transaction count belonging to a single account goes
@@ -437,17 +561,20 @@ func TestTransactionPendingLimiting(t *testing.T) {
 	state.AddBalance(account, big.NewInt(1000000))
 
 	// Keep queuing up transactions and make sure all above a limit are dropped
-	for i := uint64(0); i < maxQueued+5; i++ {
+	for i := uint64(0); i < maxQueuedPerAccount+5; i++ {
 		if err := pool.Add(transaction(i, big.NewInt(100000), key)); err != nil {
 			t.Fatalf("tx %d: failed to add transaction: %v", i, err)
 		}
-		if len(pool.pending) != int(i)+1 {
-			t.Errorf("tx %d: pending pool size mismatch: have %d, want %d", i, len(pool.pending), i+1)
+		if pool.pending[account].Len() != int(i)+1 {
+			t.Errorf("tx %d: pending pool size mismatch: have %d, want %d", i, pool.pending[account].Len(), i+1)
 		}
-		if len(pool.queue[account]) != 0 {
-			t.Errorf("tx %d: queue size mismatch: have %d, want %d", i, len(pool.queue[account]), 0)
+		if len(pool.queue) != 0 {
+			t.Errorf("tx %d: queue size mismatch: have %d, want %d", i, pool.queue[account].Len(), 0)
 		}
 	}
+	if len(pool.all) != int(maxQueuedPerAccount+5) {
+		t.Errorf("total transaction mismatch: have %d, want %d", len(pool.all), maxQueuedPerAccount+5)
+	}
 }
 
 // Tests that the transaction limits are enforced the same way irrelevant whether
@@ -462,39 +589,42 @@ func testTransactionLimitingEquivalency(t *testing.T, origin uint64) {
 	state1, _ := pool1.currentState()
 	state1.AddBalance(account1, big.NewInt(1000000))
 
-	for i := uint64(0); i < maxQueued+5; i++ {
+	for i := uint64(0); i < maxQueuedPerAccount+5; i++ {
 		if err := pool1.Add(transaction(origin+i, big.NewInt(100000), key1)); err != nil {
 			t.Fatalf("tx %d: failed to add transaction: %v", i, err)
 		}
 	}
-	// Add a batch of transactions to a pool in one bit batch
+	// Add a batch of transactions to a pool in one big batch
 	pool2, key2 := setupTxPool()
 	account2, _ := transaction(0, big.NewInt(0), key2).From()
 	state2, _ := pool2.currentState()
 	state2.AddBalance(account2, big.NewInt(1000000))
 
 	txns := []*types.Transaction{}
-	for i := uint64(0); i < maxQueued+5; i++ {
+	for i := uint64(0); i < maxQueuedPerAccount+5; i++ {
 		txns = append(txns, transaction(origin+i, big.NewInt(100000), key2))
 	}
-	pool2.AddTransactions(txns)
+	pool2.AddBatch(txns)
 
 	// Ensure the batch optimization honors the same pool mechanics
 	if len(pool1.pending) != len(pool2.pending) {
 		t.Errorf("pending transaction count mismatch: one-by-one algo: %d, batch algo: %d", len(pool1.pending), len(pool2.pending))
 	}
-	if len(pool1.queue[account1]) != len(pool2.queue[account2]) {
-		t.Errorf("queued transaction count mismatch: one-by-one algo: %d, batch algo: %d", len(pool1.queue[account1]), len(pool2.queue[account2]))
+	if len(pool1.queue) != len(pool2.queue) {
+		t.Errorf("queued transaction count mismatch: one-by-one algo: %d, batch algo: %d", len(pool1.queue), len(pool2.queue))
+	}
+	if len(pool1.all) != len(pool2.all) {
+		t.Errorf("total transaction count mismatch: one-by-one algo %d, batch algo %d", len(pool1.all), len(pool2.all))
 	}
 }
 
 // Benchmarks the speed of validating the contents of the pending queue of the
 // transaction pool.
-func BenchmarkValidatePool100(b *testing.B)   { benchmarkValidatePool(b, 100) }
-func BenchmarkValidatePool1000(b *testing.B)  { benchmarkValidatePool(b, 1000) }
-func BenchmarkValidatePool10000(b *testing.B) { benchmarkValidatePool(b, 10000) }
+func BenchmarkPendingDemotion100(b *testing.B)   { benchmarkPendingDemotion(b, 100) }
+func BenchmarkPendingDemotion1000(b *testing.B)  { benchmarkPendingDemotion(b, 1000) }
+func BenchmarkPendingDemotion10000(b *testing.B) { benchmarkPendingDemotion(b, 10000) }
 
-func benchmarkValidatePool(b *testing.B, size int) {
+func benchmarkPendingDemotion(b *testing.B, size int) {
 	// Add a batch of transactions to a pool one by one
 	pool, key := setupTxPool()
 	account, _ := transaction(0, big.NewInt(0), key).From()
@@ -503,22 +633,22 @@ func benchmarkValidatePool(b *testing.B, size int) {
 
 	for i := 0; i < size; i++ {
 		tx := transaction(uint64(i), big.NewInt(100000), key)
-		pool.addTx(tx.Hash(), account, tx)
+		pool.promoteTx(account, tx.Hash(), tx)
 	}
 	// Benchmark the speed of pool validation
 	b.ResetTimer()
 	for i := 0; i < b.N; i++ {
-		pool.validatePool()
+		pool.demoteUnexecutables()
 	}
 }
 
 // Benchmarks the speed of scheduling the contents of the future queue of the
 // transaction pool.
-func BenchmarkCheckQueue100(b *testing.B)   { benchmarkCheckQueue(b, 100) }
-func BenchmarkCheckQueue1000(b *testing.B)  { benchmarkCheckQueue(b, 1000) }
-func BenchmarkCheckQueue10000(b *testing.B) { benchmarkCheckQueue(b, 10000) }
+func BenchmarkFuturePromotion100(b *testing.B)   { benchmarkFuturePromotion(b, 100) }
+func BenchmarkFuturePromotion1000(b *testing.B)  { benchmarkFuturePromotion(b, 1000) }
+func BenchmarkFuturePromotion10000(b *testing.B) { benchmarkFuturePromotion(b, 10000) }
 
-func benchmarkCheckQueue(b *testing.B, size int) {
+func benchmarkFuturePromotion(b *testing.B, size int) {
 	// Add a batch of transactions to a pool one by one
 	pool, key := setupTxPool()
 	account, _ := transaction(0, big.NewInt(0), key).From()
@@ -527,11 +657,56 @@ func benchmarkCheckQueue(b *testing.B, size int) {
 
 	for i := 0; i < size; i++ {
 		tx := transaction(uint64(1+i), big.NewInt(100000), key)
-		pool.queueTx(tx.Hash(), tx)
+		pool.enqueueTx(tx.Hash(), tx)
 	}
 	// Benchmark the speed of pool validation
 	b.ResetTimer()
 	for i := 0; i < b.N; i++ {
-		pool.checkQueue()
+		pool.promoteExecutables()
+	}
+}
+
+// Benchmarks the speed of iterative transaction insertion.
+func BenchmarkPoolInsert(b *testing.B) {
+	// Generate a batch of transactions to enqueue into the pool
+	pool, key := setupTxPool()
+	account, _ := transaction(0, big.NewInt(0), key).From()
+	state, _ := pool.currentState()
+	state.AddBalance(account, big.NewInt(1000000))
+
+	txs := make(types.Transactions, b.N)
+	for i := 0; i < b.N; i++ {
+		txs[i] = transaction(uint64(i), big.NewInt(100000), key)
+	}
+	// Benchmark importing the transactions into the queue
+	b.ResetTimer()
+	for _, tx := range txs {
+		pool.Add(tx)
+	}
+}
+
+// Benchmarks the speed of batched transaction insertion.
+func BenchmarkPoolBatchInsert100(b *testing.B)   { benchmarkPoolBatchInsert(b, 100) }
+func BenchmarkPoolBatchInsert1000(b *testing.B)  { benchmarkPoolBatchInsert(b, 1000) }
+func BenchmarkPoolBatchInsert10000(b *testing.B) { benchmarkPoolBatchInsert(b, 10000) }
+
+func benchmarkPoolBatchInsert(b *testing.B, size int) {
+	// Generate a batch of transactions to enqueue into the pool
+	pool, key := setupTxPool()
+	account, _ := transaction(0, big.NewInt(0), key).From()
+	state, _ := pool.currentState()
+	state.AddBalance(account, big.NewInt(1000000))
+
+	batches := make([]types.Transactions, b.N)
+	for i := 0; i < b.N; i++ {
+		batches[i] = make(types.Transactions, size)
+		for j := 0; j < size; j++ {
+			batches[i][j] = transaction(uint64(size*i+j), big.NewInt(100000), key)
+		}
+	}
+	// Benchmark importing the transactions into the queue
+	b.ResetTimer()
+	for _, batch := range batches {
+		pool.AddBatch(batch)
 	}
 }
diff --git a/core/types/transaction.go b/core/types/transaction.go
index d369d7772..5bb599479 100644
--- a/core/types/transaction.go
+++ b/core/types/transaction.go
@@ -24,7 +24,6 @@ import (
 	"fmt"
 	"io"
 	"math/big"
-	"sort"
 	"sync/atomic"
 
 	"github.com/ethereum/go-ethereum/common"
@@ -427,49 +426,58 @@ func (s *TxByPrice) Pop() interface{} {
 	return x
 }
 
-// SortByPriceAndNonce sorts the transactions by price in such a way that the
-// nonce orderings within a single account are maintained.
-//
-// Note, this is not as trivial as it seems from the first look as there are three
-// different criteria that need to be taken into account (price, nonce, account
-// match), which cannot be done with any plain sorting method, as certain items
-// cannot be compared without context.
+// TransactionsByPriceAndNonce represents a set of transactions that can return
+// transactions in a profit-maximising sorted order, while supporting removing
+// entire batches of transactions for non-executable accounts.
+type TransactionsByPriceAndNonce struct {
+	txs   map[common.Address]Transactions // Per account nonce-sorted list of transactions
+	heads TxByPrice                       // Next transaction for each unique account (price heap)
+}
+
+// NewTransactionsByPriceAndNonce creates a transaction set that can retrieve
+// price sorted transactions in a nonce-honouring way.
 //
-// This method first sorts the separates the list of transactions into individual
-// sender accounts and sorts them by nonce. After the account nonce ordering is
-// satisfied, the results are merged back together by price, always comparing only
-// the head transaction from each account. This is done via a heap to keep it fast.
-func SortByPriceAndNonce(txs []*Transaction) {
-	// Separate the transactions by account and sort by nonce
-	byNonce := make(map[common.Address][]*Transaction)
-	for _, tx := range txs {
-		acc, _ := tx.From() // we only sort valid txs so this cannot fail
-		byNonce[acc] = append(byNonce[acc], tx)
+// Note, the input map is reowned so the caller should not interact any more with
+// if after providng it to the constructor.
+func NewTransactionsByPriceAndNonce(txs map[common.Address]Transactions) *TransactionsByPriceAndNonce {
+	// Initialize a price based heap with the head transactions
+	heads := make(TxByPrice, 0, len(txs))
+	for acc, accTxs := range txs {
+		heads = append(heads, accTxs[0])
+		txs[acc] = accTxs[1:]
 	}
-	for _, accTxs := range byNonce {
-		sort.Sort(TxByNonce(accTxs))
+	heap.Init(&heads)
+
+	// Assemble and return the transaction set
+	return &TransactionsByPriceAndNonce{
+		txs:   txs,
+		heads: heads,
 	}
-	// Initialize a price based heap with the head transactions
-	byPrice := make(TxByPrice, 0, len(byNonce))
-	for acc, accTxs := range byNonce {
-		byPrice = append(byPrice, accTxs[0])
-		byNonce[acc] = accTxs[1:]
+}
+
+// Peek returns the next transaction by price.
+func (t *TransactionsByPriceAndNonce) Peek() *Transaction {
+	if len(t.heads) == 0 {
+		return nil
 	}
-	heap.Init(&byPrice)
-
-	// Merge by replacing the best with the next from the same account
-	txs = txs[:0]
-	for len(byPrice) > 0 {
-		// Retrieve the next best transaction by price
-		best := heap.Pop(&byPrice).(*Transaction)
-
-		// Push in its place the next transaction from the same account
-		acc, _ := best.From() // we only sort valid txs so this cannot fail
-		if accTxs, ok := byNonce[acc]; ok && len(accTxs) > 0 {
-			heap.Push(&byPrice, accTxs[0])
-			byNonce[acc] = accTxs[1:]
-		}
-		// Accumulate the best priced transaction
-		txs = append(txs, best)
+	return t.heads[0]
+}
+
+// Shift replaces the current best head with the next one from the same account.
+func (t *TransactionsByPriceAndNonce) Shift() {
+	acc, _ := t.heads[0].From() // we only sort valid txs so this cannot fail
+
+	if txs, ok := t.txs[acc]; ok && len(txs) > 0 {
+		t.heads[0], t.txs[acc] = txs[0], txs[1:]
+		heap.Fix(&t.heads, 0)
+	} else {
+		heap.Pop(&t.heads)
 	}
 }
+
+// Pop removes the best transaction, *not* replacing it with the next one from
+// the same account. This should be used when a transaction cannot be executed
+// and hence all subsequent ones should be discarded from the same account.
+func (t *TransactionsByPriceAndNonce) Pop() {
+	heap.Pop(&t.heads)
+}
diff --git a/core/types/transaction_test.go b/core/types/transaction_test.go
index 62420e71f..8b0b02c3e 100644
--- a/core/types/transaction_test.go
+++ b/core/types/transaction_test.go
@@ -128,15 +128,25 @@ func TestTransactionPriceNonceSort(t *testing.T) {
 		keys[i], _ = crypto.GenerateKey()
 	}
 	// Generate a batch of transactions with overlapping values, but shifted nonces
-	txs := []*Transaction{}
+	groups := map[common.Address]Transactions{}
 	for start, key := range keys {
+		addr := crypto.PubkeyToAddress(key.PublicKey)
 		for i := 0; i < 25; i++ {
 			tx, _ := NewTransaction(uint64(start+i), common.Address{}, big.NewInt(100), big.NewInt(100), big.NewInt(int64(start+i)), nil).SignECDSA(key)
-			txs = append(txs, tx)
+			groups[addr] = append(groups[addr], tx)
 		}
 	}
 	// Sort the transactions and cross check the nonce ordering
-	SortByPriceAndNonce(txs)
+	txset := NewTransactionsByPriceAndNonce(groups)
+
+	txs := Transactions{}
+	for {
+		if tx := txset.Peek(); tx != nil {
+			txs = append(txs, tx)
+			txset.Shift()
+		}
+		break
+	}
 	for i, txi := range txs {
 		fromi, _ := txi.From()
 
diff --git a/eth/api_backend.go b/eth/api_backend.go
index efcdb3361..4f8f06529 100644
--- a/eth/api_backend.go
+++ b/eth/api_backend.go
@@ -118,21 +118,25 @@ func (b *EthApiBackend) RemoveTx(txHash common.Hash) {
 	b.eth.txMu.Lock()
 	defer b.eth.txMu.Unlock()
 
-	b.eth.txPool.RemoveTx(txHash)
+	b.eth.txPool.Remove(txHash)
 }
 
 func (b *EthApiBackend) GetPoolTransactions() types.Transactions {
 	b.eth.txMu.Lock()
 	defer b.eth.txMu.Unlock()
 
-	return b.eth.txPool.GetTransactions()
+	var txs types.Transactions
+	for _, batch := range b.eth.txPool.Pending() {
+		txs = append(txs, batch...)
+	}
+	return txs
 }
 
-func (b *EthApiBackend) GetPoolTransaction(txHash common.Hash) *types.Transaction {
+func (b *EthApiBackend) GetPoolTransaction(hash common.Hash) *types.Transaction {
 	b.eth.txMu.Lock()
 	defer b.eth.txMu.Unlock()
 
-	return b.eth.txPool.GetTransaction(txHash)
+	return b.eth.txPool.Get(hash)
 }
 
 func (b *EthApiBackend) GetPoolNonce(ctx context.Context, addr common.Address) (uint64, error) {
@@ -149,7 +153,7 @@ func (b *EthApiBackend) Stats() (pending int, queued int) {
 	return b.eth.txPool.Stats()
 }
 
-func (b *EthApiBackend) TxPoolContent() (map[common.Address]map[uint64][]*types.Transaction, map[common.Address]map[uint64][]*types.Transaction) {
+func (b *EthApiBackend) TxPoolContent() (map[common.Address]types.Transactions, map[common.Address]types.Transactions) {
 	b.eth.txMu.Lock()
 	defer b.eth.txMu.Unlock()
 
diff --git a/eth/handler.go b/eth/handler.go
index 570c79dac..e6c547c02 100644
--- a/eth/handler.go
+++ b/eth/handler.go
@@ -677,7 +677,7 @@ func (pm *ProtocolManager) handleMsg(p *peer) error {
 			}
 			p.MarkTransaction(tx.Hash())
 		}
-		pm.txpool.AddTransactions(txs)
+		pm.txpool.AddBatch(txs)
 
 	default:
 		return errResp(ErrInvalidMsgCode, "%v", msg.Code)
diff --git a/eth/helper_test.go b/eth/helper_test.go
index 28ff69b17..732fe89ee 100644
--- a/eth/helper_test.go
+++ b/eth/helper_test.go
@@ -23,6 +23,7 @@ import (
 	"crypto/ecdsa"
 	"crypto/rand"
 	"math/big"
+	"sort"
 	"sync"
 	"testing"
 
@@ -89,9 +90,9 @@ type testTxPool struct {
 	lock sync.RWMutex // Protects the transaction pool
 }
 
-// AddTransactions appends a batch of transactions to the pool, and notifies any
+// AddBatch appends a batch of transactions to the pool, and notifies any
 // listeners if the addition channel is non nil
-func (p *testTxPool) AddTransactions(txs []*types.Transaction) {
+func (p *testTxPool) AddBatch(txs []*types.Transaction) {
 	p.lock.Lock()
 	defer p.lock.Unlock()
 
@@ -101,15 +102,20 @@ func (p *testTxPool) AddTransactions(txs []*types.Transaction) {
 	}
 }
 
-// GetTransactions returns all the transactions known to the pool
-func (p *testTxPool) GetTransactions() types.Transactions {
+// Pending returns all the transactions known to the pool
+func (p *testTxPool) Pending() map[common.Address]types.Transactions {
 	p.lock.RLock()
 	defer p.lock.RUnlock()
 
-	txs := make([]*types.Transaction, len(p.pool))
-	copy(txs, p.pool)
-
-	return txs
+	batches := make(map[common.Address]types.Transactions)
+	for _, tx := range p.pool {
+		from, _ := tx.From()
+		batches[from] = append(batches[from], tx)
+	}
+	for _, batch := range batches {
+		sort.Sort(types.TxByNonce(batch))
+	}
+	return batches
 }
 
 // newTestTransaction create a new dummy transaction.
diff --git a/eth/protocol.go b/eth/protocol.go
index 69b3be578..3f65c204b 100644
--- a/eth/protocol.go
+++ b/eth/protocol.go
@@ -97,12 +97,12 @@ var errorToString = map[int]string{
 }
 
 type txPool interface {
-	// AddTransactions should add the given transactions to the pool.
-	AddTransactions([]*types.Transaction)
+	// AddBatch should add the given transactions to the pool.
+	AddBatch([]*types.Transaction)
 
-	// GetTransactions should return pending transactions.
+	// Pending should return pending transactions.
 	// The slice should be modifiable by the caller.
-	GetTransactions() types.Transactions
+	Pending() map[common.Address]types.Transactions
 }
 
 // statusData is the network packet for the status message.
diff --git a/eth/protocol_test.go b/eth/protocol_test.go
index 4633344da..0aac19f43 100644
--- a/eth/protocol_test.go
+++ b/eth/protocol_test.go
@@ -130,7 +130,7 @@ func testSendTransactions(t *testing.T, protocol int) {
 	for nonce := range alltxs {
 		alltxs[nonce] = newTestTransaction(testAccount, uint64(nonce), txsize)
 	}
-	pm.txpool.AddTransactions(alltxs)
+	pm.txpool.AddBatch(alltxs)
 
 	// Connect several peers. They should all receive the pending transactions.
 	var wg sync.WaitGroup
diff --git a/eth/sync.go b/eth/sync.go
index e1946edda..6584bb1e2 100644
--- a/eth/sync.go
+++ b/eth/sync.go
@@ -45,7 +45,10 @@ type txsync struct {
 
 // syncTransactions starts sending all currently pending transactions to the given peer.
 func (pm *ProtocolManager) syncTransactions(p *peer) {
-	txs := pm.txpool.GetTransactions()
+	var txs types.Transactions
+	for _, batch := range pm.txpool.Pending() {
+		txs = append(txs, batch...)
+	}
 	if len(txs) == 0 {
 		return
 	}
diff --git a/internal/ethapi/api.go b/internal/ethapi/api.go
index 184b5831f..0fba55ae8 100644
--- a/internal/ethapi/api.go
+++ b/internal/ethapi/api.go
@@ -100,32 +100,26 @@ func NewPublicTxPoolAPI(b Backend) *PublicTxPoolAPI {
 }
 
 // Content returns the transactions contained within the transaction pool.
-func (s *PublicTxPoolAPI) Content() map[string]map[string]map[string][]*RPCTransaction {
-	content := map[string]map[string]map[string][]*RPCTransaction{
-		"pending": make(map[string]map[string][]*RPCTransaction),
-		"queued":  make(map[string]map[string][]*RPCTransaction),
+func (s *PublicTxPoolAPI) Content() map[string]map[string]map[string]*RPCTransaction {
+	content := map[string]map[string]map[string]*RPCTransaction{
+		"pending": make(map[string]map[string]*RPCTransaction),
+		"queued":  make(map[string]map[string]*RPCTransaction),
 	}
 	pending, queue := s.b.TxPoolContent()
 
 	// Flatten the pending transactions
-	for account, batches := range pending {
-		dump := make(map[string][]*RPCTransaction)
-		for nonce, txs := range batches {
-			nonce := fmt.Sprintf("%d", nonce)
-			for _, tx := range txs {
-				dump[nonce] = append(dump[nonce], newRPCPendingTransaction(tx))
-			}
+	for account, txs := range pending {
+		dump := make(map[string]*RPCTransaction)
+		for nonce, tx := range txs {
+			dump[fmt.Sprintf("%d", nonce)] = newRPCPendingTransaction(tx)
 		}
 		content["pending"][account.Hex()] = dump
 	}
 	// Flatten the queued transactions
-	for account, batches := range queue {
-		dump := make(map[string][]*RPCTransaction)
-		for nonce, txs := range batches {
-			nonce := fmt.Sprintf("%d", nonce)
-			for _, tx := range txs {
-				dump[nonce] = append(dump[nonce], newRPCPendingTransaction(tx))
-			}
+	for account, txs := range queue {
+		dump := make(map[string]*RPCTransaction)
+		for nonce, tx := range txs {
+			dump[fmt.Sprintf("%d", nonce)] = newRPCPendingTransaction(tx)
 		}
 		content["queued"][account.Hex()] = dump
 	}
@@ -143,10 +137,10 @@ func (s *PublicTxPoolAPI) Status() map[string]*rpc.HexNumber {
 
 // Inspect retrieves the content of the transaction pool and flattens it into an
 // easily inspectable list.
-func (s *PublicTxPoolAPI) Inspect() map[string]map[string]map[string][]string {
-	content := map[string]map[string]map[string][]string{
-		"pending": make(map[string]map[string][]string),
-		"queued":  make(map[string]map[string][]string),
+func (s *PublicTxPoolAPI) Inspect() map[string]map[string]map[string]string {
+	content := map[string]map[string]map[string]string{
+		"pending": make(map[string]map[string]string),
+		"queued":  make(map[string]map[string]string),
 	}
 	pending, queue := s.b.TxPoolContent()
 
@@ -158,24 +152,18 @@ func (s *PublicTxPoolAPI) Inspect() map[string]map[string]map[string][]string {
 		return fmt.Sprintf("contract creation: %v wei + %v × %v gas", tx.Value(), tx.Gas(), tx.GasPrice())
 	}
 	// Flatten the pending transactions
-	for account, batches := range pending {
-		dump := make(map[string][]string)
-		for nonce, txs := range batches {
-			nonce := fmt.Sprintf("%d", nonce)
-			for _, tx := range txs {
-				dump[nonce] = append(dump[nonce], format(tx))
-			}
+	for account, txs := range pending {
+		dump := make(map[string]string)
+		for nonce, tx := range txs {
+			dump[fmt.Sprintf("%d", nonce)] = format(tx)
 		}
 		content["pending"][account.Hex()] = dump
 	}
 	// Flatten the queued transactions
-	for account, batches := range queue {
-		dump := make(map[string][]string)
-		for nonce, txs := range batches {
-			nonce := fmt.Sprintf("%d", nonce)
-			for _, tx := range txs {
-				dump[nonce] = append(dump[nonce], format(tx))
-			}
+	for account, txs := range queue {
+		dump := make(map[string]string)
+		for nonce, tx := range txs {
+			dump[fmt.Sprintf("%d", nonce)] = format(tx)
 		}
 		content["queued"][account.Hex()] = dump
 	}
diff --git a/internal/ethapi/backend.go b/internal/ethapi/backend.go
index 791a06925..0aa3da18d 100644
--- a/internal/ethapi/backend.go
+++ b/internal/ethapi/backend.go
@@ -58,7 +58,7 @@ type Backend interface {
 	GetPoolTransaction(txHash common.Hash) *types.Transaction
 	GetPoolNonce(ctx context.Context, addr common.Address) (uint64, error)
 	Stats() (pending int, queued int)
-	TxPoolContent() (map[common.Address]map[uint64][]*types.Transaction, map[common.Address]map[uint64][]*types.Transaction)
+	TxPoolContent() (map[common.Address]types.Transactions, map[common.Address]types.Transactions)
 }
 
 type State interface {
diff --git a/miner/worker.go b/miner/worker.go
index 59406bf4e..d899622b6 100644
--- a/miner/worker.go
+++ b/miner/worker.go
@@ -63,18 +63,16 @@ type uint64RingBuffer struct {
 // Work is the workers current environment and holds
 // all of the current state information
 type Work struct {
-	config             *core.ChainConfig
-	state              *state.StateDB // apply state changes here
-	ancestors          *set.Set       // ancestor set (used for checking uncle parent validity)
-	family             *set.Set       // family set (used for checking uncle invalidity)
-	uncles             *set.Set       // uncle set
-	remove             *set.Set       // tx which will be removed
-	tcount             int            // tx count in cycle
-	ignoredTransactors *set.Set
-	lowGasTransactors  *set.Set
-	ownedAccounts      *set.Set
-	lowGasTxs          types.Transactions
-	localMinedBlocks   *uint64RingBuffer // the most recent block numbers that were mined locally (used to check block inclusion)
+	config           *core.ChainConfig
+	state            *state.StateDB // apply state changes here
+	ancestors        *set.Set       // ancestor set (used for checking uncle parent validity)
+	family           *set.Set       // family set (used for checking uncle invalidity)
+	uncles           *set.Set       // uncle set
+	tcount           int            // tx count in cycle
+	ownedAccounts    *set.Set
+	lowGasTxs        types.Transactions
+	failedTxs        types.Transactions
+	localMinedBlocks *uint64RingBuffer // the most recent block numbers that were mined locally (used to check block inclusion)
 
 	Block *types.Block // the new block
 
@@ -236,7 +234,12 @@ func (self *worker) update() {
 			// Apply transaction to the pending state if we're not mining
 			if atomic.LoadInt32(&self.mining) == 0 {
 				self.currentMu.Lock()
-				self.current.commitTransactions(self.mux, types.Transactions{ev.Tx}, self.gasPrice, self.chain)
+
+				acc, _ := ev.Tx.From()
+				txs := map[common.Address]types.Transactions{acc: types.Transactions{ev.Tx}}
+				txset := types.NewTransactionsByPriceAndNonce(txs)
+
+				self.current.commitTransactions(self.mux, txset, self.gasPrice, self.chain)
 				self.currentMu.Unlock()
 			}
 		}
@@ -383,10 +386,7 @@ func (self *worker) makeCurrent(parent *types.Block, header *types.Header) error
 	accounts := self.eth.AccountManager().Accounts()
 
 	// Keep track of transactions which return errors so they can be removed
-	work.remove = set.New()
 	work.tcount = 0
-	work.ignoredTransactors = set.New()
-	work.lowGasTransactors = set.New()
 	work.ownedAccounts = accountAddressesSet(accounts)
 	if self.current != nil {
 		work.localMinedBlocks = self.current.localMinedBlocks
@@ -495,45 +495,11 @@ func (self *worker) commitNewWork() {
 	if self.config.DAOForkSupport && self.config.DAOForkBlock != nil && self.config.DAOForkBlock.Cmp(header.Number) == 0 {
 		core.ApplyDAOHardFork(work.state)
 	}
+	txs := types.NewTransactionsByPriceAndNonce(self.eth.TxPool().Pending())
+	work.commitTransactions(self.mux, txs, self.gasPrice, self.chain)
 
-	/* //approach 1
-	transactions := self.eth.TxPool().GetTransactions()
-	sort.Sort(types.TxByNonce(transactions))
-	*/
-
-	//approach 2
-	transactions := self.eth.TxPool().GetTransactions()
-	types.SortByPriceAndNonce(transactions)
-
-	/* // approach 3
-	// commit transactions for this run.
-	txPerOwner := make(map[common.Address]types.Transactions)
-	// Sort transactions by owner
-	for _, tx := range self.eth.TxPool().GetTransactions() {
-		from, _ := tx.From() // we can ignore the sender error
-		txPerOwner[from] = append(txPerOwner[from], tx)
-	}
-	var (
-		singleTxOwner types.Transactions
-		multiTxOwner  types.Transactions
-	)
-	// Categorise transactions by
-	// 1. 1 owner tx per block
-	// 2. multi txs owner per block
-	for _, txs := range txPerOwner {
-		if len(txs) == 1 {
-			singleTxOwner = append(singleTxOwner, txs[0])
-		} else {
-			multiTxOwner = append(multiTxOwner, txs...)
-		}
-	}
-	sort.Sort(types.TxByPrice(singleTxOwner))
-	sort.Sort(types.TxByNonce(multiTxOwner))
-	transactions := append(singleTxOwner, multiTxOwner...)
-	*/
-
-	work.commitTransactions(self.mux, transactions, self.gasPrice, self.chain)
-	self.eth.TxPool().RemoveTransactions(work.lowGasTxs)
+	self.eth.TxPool().RemoveBatch(work.lowGasTxs)
+	self.eth.TxPool().RemoveBatch(work.failedTxs)
 
 	// compute uncles for the new block.
 	var (
@@ -591,65 +557,51 @@ func (self *worker) commitUncle(work *Work, uncle *types.Header) error {
 	return nil
 }
 
-func (env *Work) commitTransactions(mux *event.TypeMux, transactions types.Transactions, gasPrice *big.Int, bc *core.BlockChain) {
+func (env *Work) commitTransactions(mux *event.TypeMux, txs *types.TransactionsByPriceAndNonce, gasPrice *big.Int, bc *core.BlockChain) {
 	gp := new(core.GasPool).AddGas(env.header.GasLimit)
 
 	var coalescedLogs vm.Logs
-	for _, tx := range transactions {
+	for {
+		// Retrieve the next transaction and abort if all done
+		tx := txs.Peek()
+		if tx == nil {
+			break
+		}
 		// Error may be ignored here. The error has already been checked
 		// during transaction acceptance is the transaction pool.
 		from, _ := tx.From()
 
-		// Check if it falls within margin. Txs from owned accounts are always processed.
+		// Ignore any transactions (and accounts subsequently) with low gas limits
 		if tx.GasPrice().Cmp(gasPrice) < 0 && !env.ownedAccounts.Has(from) {
-			// ignore the transaction and transactor. We ignore the transactor
-			// because nonce will fail after ignoring this transaction so there's
-			// no point
-			env.lowGasTransactors.Add(from)
-
-			glog.V(logger.Info).Infof("transaction(%x) below gas price (tx=%v ask=%v). All sequential txs from this address(%x) will be ignored\n", tx.Hash().Bytes()[:4], common.CurrencyToString(tx.GasPrice()), common.CurrencyToString(gasPrice), from[:4])
-		}
+			// Pop the current low-priced transaction without shifting in the next from the account
+			glog.V(logger.Info).Infof("Transaction (%x) below gas price (tx=%v ask=%v). All sequential txs from this address(%x) will be ignored\n", tx.Hash().Bytes()[:4], common.CurrencyToString(tx.GasPrice()), common.CurrencyToString(gasPrice), from[:4])
 
-		// Continue with the next transaction if the transaction sender is included in
-		// the low gas tx set. This will also remove the tx and all sequential transaction
-		// from this transactor
-		if env.lowGasTransactors.Has(from) {
-			// add tx to the low gas set. This will be removed at the end of the run
-			// owned accounts are ignored
-			if !env.ownedAccounts.Has(from) {
-				env.lowGasTxs = append(env.lowGasTxs, tx)
-			}
-			continue
-		}
+			env.lowGasTxs = append(env.lowGasTxs, tx)
+			txs.Pop()
 
-		// Move on to the next transaction when the transactor is in ignored transactions set
-		// This may occur when a transaction hits the gas limit. When a gas limit is hit and
-		// the transaction is processed (that could potentially be included in the block) it
-		// will throw a nonce error because the previous transaction hasn't been processed.
-		// Therefor we need to ignore any transaction after the ignored one.
-		if env.ignoredTransactors.Has(from) {
 			continue
 		}
-
+		// Start executing the transaction
 		env.state.StartRecord(tx.Hash(), common.Hash{}, 0)
 
 		err, logs := env.commitTransaction(tx, bc, gp)
 		switch {
 		case core.IsGasLimitErr(err):
-			// ignore the transactor so no nonce errors will be thrown for this account
-			// next time the worker is run, they'll be picked up again.
-			env.ignoredTransactors.Add(from)
-
+			// Pop the current out-of-gas transaction without shifting in the next from the account
 			glog.V(logger.Detail).Infof("Gas limit reached for (%x) in this block. Continue to try smaller txs\n", from[:4])
+			txs.Pop()
+
 		case err != nil:
-			env.remove.Add(tx.Hash())
+			// Pop the current failed transaction without shifting in the next from the account
+			glog.V(logger.Detail).Infof("Transaction (%x) failed, will be removed: %v\n", tx.Hash().Bytes()[:4], err)
+			env.failedTxs = append(env.failedTxs, tx)
+			txs.Pop()
 
-			if glog.V(logger.Detail) {
-				glog.Infof("TX (%x) failed, will be removed: %v\n", tx.Hash().Bytes()[:4], err)
-			}
 		default:
-			env.tcount++
+			// Everything ok, collect the logs and shift in the next transaction from the same account
 			coalescedLogs = append(coalescedLogs, logs...)
+			env.tcount++
+			txs.Shift()
 		}
 	}
 	if len(coalescedLogs) > 0 || env.tcount > 0 {