Merge pull request #3216 from karalabe/fastsync-bigdb-tuning

core/state, eth/downloader, trie: reset fast-failure on progress

7 files changed, 273 insertions, 195 deletions

diff --git a/core/state/sync.go b/core/state/sync.go
index ef2b4b84c..bab9c8e7e 100644
--- a/core/state/sync.go
+++ b/core/state/sync.go
@@ -59,8 +59,10 @@ func (s *StateSync) Missing(max int) []common.Hash {
 	return (*trie.TrieSync)(s).Missing(max)
 }
 
-// Process injects a batch of retrieved trie nodes data.
-func (s *StateSync) Process(list []trie.SyncResult) (int, error) {
+// Process injects a batch of retrieved trie nodes data, returning if something
+// was committed to the database and also the index of an entry if processing of
+// it failed.
+func (s *StateSync) Process(list []trie.SyncResult) (bool, int, error) {
 	return (*trie.TrieSync)(s).Process(list)
 }
 
diff --git a/core/state/sync_test.go b/core/state/sync_test.go
index 949df7301..f5390d80f 100644
--- a/core/state/sync_test.go
+++ b/core/state/sync_test.go
@@ -138,7 +138,7 @@ func testIterativeStateSync(t *testing.T, batch int) {
 			}
 			results[i] = trie.SyncResult{Hash: hash, Data: data}
 		}
-		if index, err := sched.Process(results); err != nil {
+		if _, index, err := sched.Process(results); err != nil {
 			t.Fatalf("failed to process result #%d: %v", index, err)
 		}
 		queue = append(queue[:0], sched.Missing(batch)...)
@@ -168,7 +168,7 @@ func TestIterativeDelayedStateSync(t *testing.T) {
 			}
 			results[i] = trie.SyncResult{Hash: hash, Data: data}
 		}
-		if index, err := sched.Process(results); err != nil {
+		if _, index, err := sched.Process(results); err != nil {
 			t.Fatalf("failed to process result #%d: %v", index, err)
 		}
 		queue = append(queue[len(results):], sched.Missing(0)...)
@@ -206,7 +206,7 @@ func testIterativeRandomStateSync(t *testing.T, batch int) {
 			results = append(results, trie.SyncResult{Hash: hash, Data: data})
 		}
 		// Feed the retrieved results back and queue new tasks
-		if index, err := sched.Process(results); err != nil {
+		if _, index, err := sched.Process(results); err != nil {
 			t.Fatalf("failed to process result #%d: %v", index, err)
 		}
 		queue = make(map[common.Hash]struct{})
@@ -249,7 +249,7 @@ func TestIterativeRandomDelayedStateSync(t *testing.T) {
 			}
 		}
 		// Feed the retrieved results back and queue new tasks
-		if index, err := sched.Process(results); err != nil {
+		if _, index, err := sched.Process(results); err != nil {
 			t.Fatalf("failed to process result #%d: %v", index, err)
 		}
 		for _, hash := range sched.Missing(0) {
@@ -283,7 +283,7 @@ func TestIncompleteStateSync(t *testing.T) {
 			results[i] = trie.SyncResult{Hash: hash, Data: data}
 		}
 		// Process each of the state nodes
-		if index, err := sched.Process(results); err != nil {
+		if _, index, err := sched.Process(results); err != nil {
 			t.Fatalf("failed to process result #%d: %v", index, err)
 		}
 		for _, result := range results {
diff --git a/eth/downloader/downloader.go b/eth/downloader/downloader.go
index 987be2b7a..da20e48a2 100644
--- a/eth/downloader/downloader.go
+++ b/eth/downloader/downloader.go
@@ -64,12 +64,12 @@ var (
 	maxHeadersProcess = 2048      // Number of header download results to import at once into the chain
 	maxResultsProcess = 2048      // Number of content download results to import at once into the chain
 
-	fsHeaderCheckFrequency = 100  // Verification frequency of the downloaded headers during fast sync
-	fsHeaderSafetyNet      = 2048 // Number of headers to discard in case a chain violation is detected
-	fsHeaderForceVerify    = 24   // Number of headers to verify before and after the pivot to accept it
-	fsPivotInterval        = 512  // Number of headers out of which to randomize the pivot point
-	fsMinFullBlocks        = 1024 // Number of blocks to retrieve fully even in fast sync
-	fsCriticalTrials       = 10   // Number of times to retry in the cricical section before bailing
+	fsHeaderCheckFrequency = 100        // Verification frequency of the downloaded headers during fast sync
+	fsHeaderSafetyNet      = 2048       // Number of headers to discard in case a chain violation is detected
+	fsHeaderForceVerify    = 24         // Number of headers to verify before and after the pivot to accept it
+	fsPivotInterval        = 256        // Number of headers out of which to randomize the pivot point
+	fsMinFullBlocks        = 64         // Number of blocks to retrieve fully even in fast sync
+	fsCriticalTrials       = uint32(32) // Number of times to retry in the cricical section before bailing
 )
 
 var (
@@ -105,7 +105,7 @@ type Downloader struct {
 	peers *peerSet // Set of active peers from which download can proceed
 
 	fsPivotLock  *types.Header // Pivot header on critical section entry (cannot change between retries)
-	fsPivotFails int           // Number of fast sync failures in the critical section
+	fsPivotFails uint32        // Number of subsequent fast sync failures in the critical section
 
 	rttEstimate   uint64 // Round trip time to target for download requests
 	rttConfidence uint64 // Confidence in the estimated RTT (unit: millionths to allow atomic ops)
@@ -361,7 +361,7 @@ func (d *Downloader) synchronise(id string, hash common.Hash, td *big.Int, mode
 
 	// Set the requested sync mode, unless it's forbidden
 	d.mode = mode
-	if d.mode == FastSync && d.fsPivotFails >= fsCriticalTrials {
+	if d.mode == FastSync && atomic.LoadUint32(&d.fsPivotFails) >= fsCriticalTrials {
 		d.mode = FullSync
 	}
 	// Retrieve the origin peer and initiate the downloading process
@@ -480,6 +480,11 @@ func (d *Downloader) spawnSync(origin uint64, fetchers ...func() error) error {
 	d.queue.Close()
 	d.cancel()
 	wg.Wait()
+
+	// If sync failed in the critical section, bump the fail counter
+	if err != nil && d.mode == FastSync && d.fsPivotLock != nil {
+		atomic.AddUint32(&d.fsPivotFails, 1)
+	}
 	return err
 }
 
@@ -926,10 +931,10 @@ func (d *Downloader) fetchNodeData() error {
 	var (
 		deliver = func(packet dataPack) (int, error) {
 			start := time.Now()
-			return d.queue.DeliverNodeData(packet.PeerId(), packet.(*statePack).states, func(err error, delivered int) {
+			return d.queue.DeliverNodeData(packet.PeerId(), packet.(*statePack).states, func(delivered int, progressed bool, err error) {
 				// If the peer returned old-requested data, forgive
 				if err == trie.ErrNotRequested {
-					glog.V(logger.Info).Infof("peer %s: replied to stale state request, forgiving", packet.PeerId())
+					glog.V(logger.Debug).Infof("peer %s: replied to stale state request, forgiving", packet.PeerId())
 					return
 				}
 				if err != nil {
@@ -951,6 +956,11 @@ func (d *Downloader) fetchNodeData() error {
 				syncStatsStateDone := d.syncStatsStateDone // Thread safe copy for the log below
 				d.syncStatsLock.Unlock()
 
+				// If real database progress was made, reset any fast-sync pivot failure
+				if progressed && atomic.LoadUint32(&d.fsPivotFails) > 1 {
+					glog.V(logger.Debug).Infof("fast-sync progressed, resetting fail counter from %d", atomic.LoadUint32(&d.fsPivotFails))
+					atomic.StoreUint32(&d.fsPivotFails, 1) // Don't ever reset to 0, as that will unlock the pivot block
+				}
 				// Log a message to the user and return
 				if delivered > 0 {
 					glog.V(logger.Info).Infof("imported %3d state entries in %9v: processed %d, pending at least %d", delivered, common.PrettyDuration(time.Since(start)), syncStatsStateDone, pending)
@@ -1177,7 +1187,7 @@ func (d *Downloader) processHeaders(origin uint64, td *big.Int) error {
 			// If we're already past the pivot point, this could be an attack, thread carefully
 			if rollback[len(rollback)-1].Number.Uint64() > pivot {
 				// If we didn't ever fail, lock in te pivot header (must! not! change!)
-				if d.fsPivotFails == 0 {
+				if atomic.LoadUint32(&d.fsPivotFails) == 0 {
 					for _, header := range rollback {
 						if header.Number.Uint64() == pivot {
 							glog.V(logger.Warn).Infof("Fast-sync critical section failure, locked pivot to header #%d [%x…]", pivot, header.Hash().Bytes()[:4])
@@ -1185,7 +1195,6 @@ func (d *Downloader) processHeaders(origin uint64, td *big.Int) error {
 						}
 					}
 				}
-				d.fsPivotFails++
 			}
 		}
 	}()
diff --git a/eth/downloader/downloader_test.go b/eth/downloader/downloader_test.go
index 366c248bb..2849712ab 100644
--- a/eth/downloader/downloader_test.go
+++ b/eth/downloader/downloader_test.go
@@ -37,25 +37,79 @@ import (
 )
 
 var (
-	testdb, _   = ethdb.NewMemDatabase()
 	testKey, _  = crypto.HexToECDSA("b71c71a67e1177ad4e901695e1b4b9ee17ae16c6668d313eac2f96dbcda3f291")
 	testAddress = crypto.PubkeyToAddress(testKey.PublicKey)
-	genesis     = core.GenesisBlockForTesting(testdb, testAddress, big.NewInt(1000000000))
 )
 
 // Reduce some of the parameters to make the tester faster.
 func init() {
 	MaxForkAncestry = uint64(10000)
 	blockCacheLimit = 1024
+	fsCriticalTrials = 10
+}
+
+// downloadTester is a test simulator for mocking out local block chain.
+type downloadTester struct {
+	downloader *Downloader
+
+	genesis *types.Block   // Genesis blocks used by the tester and peers
+	stateDb ethdb.Database // Database used by the tester for syncing from peers
+	peerDb  ethdb.Database // Database of the peers containing all data
+
+	ownHashes   []common.Hash                  // Hash chain belonging to the tester
+	ownHeaders  map[common.Hash]*types.Header  // Headers belonging to the tester
+	ownBlocks   map[common.Hash]*types.Block   // Blocks belonging to the tester
+	ownReceipts map[common.Hash]types.Receipts // Receipts belonging to the tester
+	ownChainTd  map[common.Hash]*big.Int       // Total difficulties of the blocks in the local chain
+
+	peerHashes   map[string][]common.Hash                  // Hash chain belonging to different test peers
+	peerHeaders  map[string]map[common.Hash]*types.Header  // Headers belonging to different test peers
+	peerBlocks   map[string]map[common.Hash]*types.Block   // Blocks belonging to different test peers
+	peerReceipts map[string]map[common.Hash]types.Receipts // Receipts belonging to different test peers
+	peerChainTds map[string]map[common.Hash]*big.Int       // Total difficulties of the blocks in the peer chains
+
+	peerMissingStates map[string]map[common.Hash]bool // State entries that fast sync should not return
+
+	lock sync.RWMutex
+}
+
+// newTester creates a new downloader test mocker.
+func newTester() *downloadTester {
+	testdb, _ := ethdb.NewMemDatabase()
+	genesis := core.GenesisBlockForTesting(testdb, testAddress, big.NewInt(1000000000))
+
+	tester := &downloadTester{
+		genesis:           genesis,
+		peerDb:            testdb,
+		ownHashes:         []common.Hash{genesis.Hash()},
+		ownHeaders:        map[common.Hash]*types.Header{genesis.Hash(): genesis.Header()},
+		ownBlocks:         map[common.Hash]*types.Block{genesis.Hash(): genesis},
+		ownReceipts:       map[common.Hash]types.Receipts{genesis.Hash(): nil},
+		ownChainTd:        map[common.Hash]*big.Int{genesis.Hash(): genesis.Difficulty()},
+		peerHashes:        make(map[string][]common.Hash),
+		peerHeaders:       make(map[string]map[common.Hash]*types.Header),
+		peerBlocks:        make(map[string]map[common.Hash]*types.Block),
+		peerReceipts:      make(map[string]map[common.Hash]types.Receipts),
+		peerChainTds:      make(map[string]map[common.Hash]*big.Int),
+		peerMissingStates: make(map[string]map[common.Hash]bool),
+	}
+	tester.stateDb, _ = ethdb.NewMemDatabase()
+	tester.stateDb.Put(genesis.Root().Bytes(), []byte{0x00})
+
+	tester.downloader = New(tester.stateDb, new(event.TypeMux), tester.hasHeader, tester.hasBlock, tester.getHeader,
+		tester.getBlock, tester.headHeader, tester.headBlock, tester.headFastBlock, tester.commitHeadBlock, tester.getTd,
+		tester.insertHeaders, tester.insertBlocks, tester.insertReceipts, tester.rollback, tester.dropPeer)
+
+	return tester
 }
 
 // makeChain creates a chain of n blocks starting at and including parent.
 // the returned hash chain is ordered head->parent. In addition, every 3rd block
 // contains a transaction and every 5th an uncle to allow testing correct block
 // reassembly.
-func makeChain(n int, seed byte, parent *types.Block, parentReceipts types.Receipts, heavy bool) ([]common.Hash, map[common.Hash]*types.Header, map[common.Hash]*types.Block, map[common.Hash]types.Receipts) {
+func (dl *downloadTester) makeChain(n int, seed byte, parent *types.Block, parentReceipts types.Receipts, heavy bool) ([]common.Hash, map[common.Hash]*types.Header, map[common.Hash]*types.Block, map[common.Hash]types.Receipts) {
 	// Generate the block chain
-	blocks, receipts := core.GenerateChain(nil, parent, testdb, n, func(i int, block *core.BlockGen) {
+	blocks, receipts := core.GenerateChain(nil, parent, dl.peerDb, n, func(i int, block *core.BlockGen) {
 		block.SetCoinbase(common.Address{seed})
 
 		// If a heavy chain is requested, delay blocks to raise difficulty
@@ -63,7 +117,7 @@ func makeChain(n int, seed byte, parent *types.Block, parentReceipts types.Recei
 			block.OffsetTime(-1)
 		}
 		// If the block number is multiple of 3, send a bonus transaction to the miner
-		if parent == genesis && i%3 == 0 {
+		if parent == dl.genesis && i%3 == 0 {
 			tx, err := types.NewTransaction(block.TxNonce(testAddress), common.Address{seed}, big.NewInt(1000), params.TxGas, nil, nil).SignECDSA(testKey)
 			if err != nil {
 				panic(err)
@@ -102,19 +156,19 @@ func makeChain(n int, seed byte, parent *types.Block, parentReceipts types.Recei
 
 // makeChainFork creates two chains of length n, such that h1[:f] and
 // h2[:f] are different but have a common suffix of length n-f.
-func makeChainFork(n, f int, parent *types.Block, parentReceipts types.Receipts, balanced bool) ([]common.Hash, []common.Hash, map[common.Hash]*types.Header, map[common.Hash]*types.Header, map[common.Hash]*types.Block, map[common.Hash]*types.Block, map[common.Hash]types.Receipts, map[common.Hash]types.Receipts) {
+func (dl *downloadTester) makeChainFork(n, f int, parent *types.Block, parentReceipts types.Receipts, balanced bool) ([]common.Hash, []common.Hash, map[common.Hash]*types.Header, map[common.Hash]*types.Header, map[common.Hash]*types.Block, map[common.Hash]*types.Block, map[common.Hash]types.Receipts, map[common.Hash]types.Receipts) {
 	// Create the common suffix
-	hashes, headers, blocks, receipts := makeChain(n-f, 0, parent, parentReceipts, false)
+	hashes, headers, blocks, receipts := dl.makeChain(n-f, 0, parent, parentReceipts, false)
 
 	// Create the forks, making the second heavyer if non balanced forks were requested
-	hashes1, headers1, blocks1, receipts1 := makeChain(f, 1, blocks[hashes[0]], receipts[hashes[0]], false)
+	hashes1, headers1, blocks1, receipts1 := dl.makeChain(f, 1, blocks[hashes[0]], receipts[hashes[0]], false)
 	hashes1 = append(hashes1, hashes[1:]...)
 
 	heavy := false
 	if !balanced {
 		heavy = true
 	}
-	hashes2, headers2, blocks2, receipts2 := makeChain(f, 2, blocks[hashes[0]], receipts[hashes[0]], heavy)
+	hashes2, headers2, blocks2, receipts2 := dl.makeChain(f, 2, blocks[hashes[0]], receipts[hashes[0]], heavy)
 	hashes2 = append(hashes2, hashes[1:]...)
 
 	for hash, header := range headers {
@@ -132,53 +186,6 @@ func makeChainFork(n, f int, parent *types.Block, parentReceipts types.Receipts,
 	return hashes1, hashes2, headers1, headers2, blocks1, blocks2, receipts1, receipts2
 }
 
-// downloadTester is a test simulator for mocking out local block chain.
-type downloadTester struct {
-	stateDb    ethdb.Database
-	downloader *Downloader
-
-	ownHashes   []common.Hash                  // Hash chain belonging to the tester
-	ownHeaders  map[common.Hash]*types.Header  // Headers belonging to the tester
-	ownBlocks   map[common.Hash]*types.Block   // Blocks belonging to the tester
-	ownReceipts map[common.Hash]types.Receipts // Receipts belonging to the tester
-	ownChainTd  map[common.Hash]*big.Int       // Total difficulties of the blocks in the local chain
-
-	peerHashes   map[string][]common.Hash                  // Hash chain belonging to different test peers
-	peerHeaders  map[string]map[common.Hash]*types.Header  // Headers belonging to different test peers
-	peerBlocks   map[string]map[common.Hash]*types.Block   // Blocks belonging to different test peers
-	peerReceipts map[string]map[common.Hash]types.Receipts // Receipts belonging to different test peers
-	peerChainTds map[string]map[common.Hash]*big.Int       // Total difficulties of the blocks in the peer chains
-
-	peerMissingStates map[string]map[common.Hash]bool // State entries that fast sync should not return
-
-	lock sync.RWMutex
-}
-
-// newTester creates a new downloader test mocker.
-func newTester() *downloadTester {
-	tester := &downloadTester{
-		ownHashes:         []common.Hash{genesis.Hash()},
-		ownHeaders:        map[common.Hash]*types.Header{genesis.Hash(): genesis.Header()},
-		ownBlocks:         map[common.Hash]*types.Block{genesis.Hash(): genesis},
-		ownReceipts:       map[common.Hash]types.Receipts{genesis.Hash(): nil},
-		ownChainTd:        map[common.Hash]*big.Int{genesis.Hash(): genesis.Difficulty()},
-		peerHashes:        make(map[string][]common.Hash),
-		peerHeaders:       make(map[string]map[common.Hash]*types.Header),
-		peerBlocks:        make(map[string]map[common.Hash]*types.Block),
-		peerReceipts:      make(map[string]map[common.Hash]types.Receipts),
-		peerChainTds:      make(map[string]map[common.Hash]*big.Int),
-		peerMissingStates: make(map[string]map[common.Hash]bool),
-	}
-	tester.stateDb, _ = ethdb.NewMemDatabase()
-	tester.stateDb.Put(genesis.Root().Bytes(), []byte{0x00})
-
-	tester.downloader = New(tester.stateDb, new(event.TypeMux), tester.hasHeader, tester.hasBlock, tester.getHeader,
-		tester.getBlock, tester.headHeader, tester.headBlock, tester.headFastBlock, tester.commitHeadBlock, tester.getTd,
-		tester.insertHeaders, tester.insertBlocks, tester.insertReceipts, tester.rollback, tester.dropPeer)
-
-	return tester
-}
-
 // terminate aborts any operations on the embedded downloader and releases all
 // held resources.
 func (dl *downloadTester) terminate() {
@@ -251,7 +258,7 @@ func (dl *downloadTester) headHeader() *types.Header {
 			return header
 		}
 	}
-	return genesis.Header()
+	return dl.genesis.Header()
 }
 
 // headBlock retrieves the current head block from the canonical chain.
@@ -266,7 +273,7 @@ func (dl *downloadTester) headBlock() *types.Block {
 			}
 		}
 	}
-	return genesis
+	return dl.genesis
 }
 
 // headFastBlock retrieves the current head fast-sync block from the canonical chain.
@@ -279,7 +286,7 @@ func (dl *downloadTester) headFastBlock() *types.Block {
 			return block
 		}
 	}
-	return genesis
+	return dl.genesis
 }
 
 // commitHeadBlock manually sets the head block to a given hash.
@@ -351,7 +358,7 @@ func (dl *downloadTester) insertBlocks(blocks types.Blocks) (int, error) {
 	return len(blocks), nil
 }
 
-// insertReceipts injects a new batch of blocks into the simulated chain.
+// insertReceipts injects a new batch of receipts into the simulated chain.
 func (dl *downloadTester) insertReceipts(blocks types.Blocks, receipts []types.Receipts) (int, error) {
 	dl.lock.Lock()
 	defer dl.lock.Unlock()
@@ -586,7 +593,7 @@ func (dl *downloadTester) peerGetNodeDataFn(id string, delay time.Duration) func
 
 		results := make([][]byte, 0, len(hashes))
 		for _, hash := range hashes {
-			if data, err := testdb.Get(hash.Bytes()); err == nil {
+			if data, err := dl.peerDb.Get(hash.Bytes()); err == nil {
 				if !dl.peerMissingStates[id][hash] {
 					results = append(results, data)
 				}
@@ -669,13 +676,13 @@ func TestCanonicalSynchronisation64Light(t *testing.T) { testCanonicalSynchronis
 func testCanonicalSynchronisation(t *testing.T, protocol int, mode SyncMode) {
 	t.Parallel()
 
-	// Create a small enough block chain to download
-	targetBlocks := blockCacheLimit - 15
-	hashes, headers, blocks, receipts := makeChain(targetBlocks, 0, genesis, nil, false)
-
 	tester := newTester()
 	defer tester.terminate()
 
+	// Create a small enough block chain to download
+	targetBlocks := blockCacheLimit - 15
+	hashes, headers, blocks, receipts := tester.makeChain(targetBlocks, 0, tester.genesis, nil, false)
+
 	tester.newPeer("peer", protocol, hashes, headers, blocks, receipts)
 
 	// Synchronise with the peer and make sure all relevant data was retrieved
@@ -694,13 +701,13 @@ func TestThrottling64Full(t *testing.T) { testThrottling(t, 64, FullSync) }
 func TestThrottling64Fast(t *testing.T) { testThrottling(t, 64, FastSync) }
 
 func testThrottling(t *testing.T, protocol int, mode SyncMode) {
-	// Create a long block chain to download and the tester
-	targetBlocks := 8 * blockCacheLimit
-	hashes, headers, blocks, receipts := makeChain(targetBlocks, 0, genesis, nil, false)
-
 	tester := newTester()
 	defer tester.terminate()
 
+	// Create a long block chain to download and the tester
+	targetBlocks := 8 * blockCacheLimit
+	hashes, headers, blocks, receipts := tester.makeChain(targetBlocks, 0, tester.genesis, nil, false)
+
 	tester.newPeer("peer", protocol, hashes, headers, blocks, receipts)
 
 	// Wrap the importer to allow stepping
@@ -782,13 +789,13 @@ func TestForkedSync64Light(t *testing.T) { testForkedSync(t, 64, LightSync) }
 func testForkedSync(t *testing.T, protocol int, mode SyncMode) {
 	t.Parallel()
 
-	// Create a long enough forked chain
-	common, fork := MaxHashFetch, 2*MaxHashFetch
-	hashesA, hashesB, headersA, headersB, blocksA, blocksB, receiptsA, receiptsB := makeChainFork(common+fork, fork, genesis, nil, true)
-
 	tester := newTester()
 	defer tester.terminate()
 
+	// Create a long enough forked chain
+	common, fork := MaxHashFetch, 2*MaxHashFetch
+	hashesA, hashesB, headersA, headersB, blocksA, blocksB, receiptsA, receiptsB := tester.makeChainFork(common+fork, fork, tester.genesis, nil, true)
+
 	tester.newPeer("fork A", protocol, hashesA, headersA, blocksA, receiptsA)
 	tester.newPeer("fork B", protocol, hashesB, headersB, blocksB, receiptsB)
 
@@ -817,13 +824,13 @@ func TestHeavyForkedSync64Light(t *testing.T) { testHeavyForkedSync(t, 64, Light
 func testHeavyForkedSync(t *testing.T, protocol int, mode SyncMode) {
 	t.Parallel()
 
-	// Create a long enough forked chain
-	common, fork := MaxHashFetch, 4*MaxHashFetch
-	hashesA, hashesB, headersA, headersB, blocksA, blocksB, receiptsA, receiptsB := makeChainFork(common+fork, fork, genesis, nil, false)
-
 	tester := newTester()
 	defer tester.terminate()
 
+	// Create a long enough forked chain
+	common, fork := MaxHashFetch, 4*MaxHashFetch
+	hashesA, hashesB, headersA, headersB, blocksA, blocksB, receiptsA, receiptsB := tester.makeChainFork(common+fork, fork, tester.genesis, nil, false)
+
 	tester.newPeer("light", protocol, hashesA, headersA, blocksA, receiptsA)
 	tester.newPeer("heavy", protocol, hashesB[fork/2:], headersB, blocksB, receiptsB)
 
@@ -853,13 +860,13 @@ func TestBoundedForkedSync64Light(t *testing.T) { testBoundedForkedSync(t, 64, L
 func testBoundedForkedSync(t *testing.T, protocol int, mode SyncMode) {
 	t.Parallel()
 
-	// Create a long enough forked chain
-	common, fork := 13, int(MaxForkAncestry+17)
-	hashesA, hashesB, headersA, headersB, blocksA, blocksB, receiptsA, receiptsB := makeChainFork(common+fork, fork, genesis, nil, true)
-
 	tester := newTester()
 	defer tester.terminate()
 
+	// Create a long enough forked chain
+	common, fork := 13, int(MaxForkAncestry+17)
+	hashesA, hashesB, headersA, headersB, blocksA, blocksB, receiptsA, receiptsB := tester.makeChainFork(common+fork, fork, tester.genesis, nil, true)
+
 	tester.newPeer("original", protocol, hashesA, headersA, blocksA, receiptsA)
 	tester.newPeer("rewriter", protocol, hashesB, headersB, blocksB, receiptsB)
 
@@ -888,13 +895,13 @@ func TestBoundedHeavyForkedSync64Light(t *testing.T) { testBoundedHeavyForkedSyn
 func testBoundedHeavyForkedSync(t *testing.T, protocol int, mode SyncMode) {
 	t.Parallel()
 
-	// Create a long enough forked chain
-	common, fork := 13, int(MaxForkAncestry+17)
-	hashesA, hashesB, headersA, headersB, blocksA, blocksB, receiptsA, receiptsB := makeChainFork(common+fork, fork, genesis, nil, false)
-
 	tester := newTester()
 	defer tester.terminate()
 
+	// Create a long enough forked chain
+	common, fork := 13, int(MaxForkAncestry+17)
+	hashesA, hashesB, headersA, headersB, blocksA, blocksB, receiptsA, receiptsB := tester.makeChainFork(common+fork, fork, tester.genesis, nil, false)
+
 	tester.newPeer("original", protocol, hashesA, headersA, blocksA, receiptsA)
 	tester.newPeer("heavy-rewriter", protocol, hashesB[MaxForkAncestry-17:], headersB, blocksB, receiptsB) // Root the fork below the ancestor limit
 
@@ -958,6 +965,9 @@ func TestCancel64Light(t *testing.T) { testCancel(t, 64, LightSync) }
 func testCancel(t *testing.T, protocol int, mode SyncMode) {
 	t.Parallel()
 
+	tester := newTester()
+	defer tester.terminate()
+
 	// Create a small enough block chain to download and the tester
 	targetBlocks := blockCacheLimit - 15
 	if targetBlocks >= MaxHashFetch {
@@ -966,10 +976,7 @@ func testCancel(t *testing.T, protocol int, mode SyncMode) {
 	if targetBlocks >= MaxHeaderFetch {
 		targetBlocks = MaxHeaderFetch - 15
 	}
-	hashes, headers, blocks, receipts := makeChain(targetBlocks, 0, genesis, nil, false)
-
-	tester := newTester()
-	defer tester.terminate()
+	hashes, headers, blocks, receipts := tester.makeChain(targetBlocks, 0, tester.genesis, nil, false)
 
 	tester.newPeer("peer", protocol, hashes, headers, blocks, receipts)
 
@@ -999,13 +1006,13 @@ func TestMultiSynchronisation64Light(t *testing.T) { testMultiSynchronisation(t,
 func testMultiSynchronisation(t *testing.T, protocol int, mode SyncMode) {
 	t.Parallel()
 
+	tester := newTester()
+	defer tester.terminate()
+
 	// Create various peers with various parts of the chain
 	targetPeers := 8
 	targetBlocks := targetPeers*blockCacheLimit - 15
-	hashes, headers, blocks, receipts := makeChain(targetBlocks, 0, genesis, nil, false)
-
-	tester := newTester()
-	defer tester.terminate()
+	hashes, headers, blocks, receipts := tester.makeChain(targetBlocks, 0, tester.genesis, nil, false)
 
 	for i := 0; i < targetPeers; i++ {
 		id := fmt.Sprintf("peer #%d", i)
@@ -1029,14 +1036,14 @@ func TestMultiProtoSynchronisation64Light(t *testing.T) { testMultiProtoSync(t,
 func testMultiProtoSync(t *testing.T, protocol int, mode SyncMode) {
 	t.Parallel()
 
+	tester := newTester()
+	defer tester.terminate()
+
 	// Create a small enough block chain to download
 	targetBlocks := blockCacheLimit - 15
-	hashes, headers, blocks, receipts := makeChain(targetBlocks, 0, genesis, nil, false)
+	hashes, headers, blocks, receipts := tester.makeChain(targetBlocks, 0, tester.genesis, nil, false)
 
 	// Create peers of every type
-	tester := newTester()
-	defer tester.terminate()
-
 	tester.newPeer("peer 62", 62, hashes, headers, blocks, nil)
 	tester.newPeer("peer 63", 63, hashes, headers, blocks, receipts)
 	tester.newPeer("peer 64", 64, hashes, headers, blocks, receipts)
@@ -1068,13 +1075,13 @@ func TestEmptyShortCircuit64Light(t *testing.T) { testEmptyShortCircuit(t, 64, L
 func testEmptyShortCircuit(t *testing.T, protocol int, mode SyncMode) {
 	t.Parallel()
 
-	// Create a block chain to download
-	targetBlocks := 2*blockCacheLimit - 15
-	hashes, headers, blocks, receipts := makeChain(targetBlocks, 0, genesis, nil, false)
-
 	tester := newTester()
 	defer tester.terminate()
 
+	// Create a block chain to download
+	targetBlocks := 2*blockCacheLimit - 15
+	hashes, headers, blocks, receipts := tester.makeChain(targetBlocks, 0, tester.genesis, nil, false)
+
 	tester.newPeer("peer", protocol, hashes, headers, blocks, receipts)
 
 	// Instrument the downloader to signal body requests
@@ -1094,7 +1101,7 @@ func testEmptyShortCircuit(t *testing.T, protocol int, mode SyncMode) {
 	// Validate the number of block bodies that should have been requested
 	bodiesNeeded, receiptsNeeded := 0, 0
 	for _, block := range blocks {
-		if mode != LightSync && block != genesis && (len(block.Transactions()) > 0 || len(block.Uncles()) > 0) {
+		if mode != LightSync && block != tester.genesis && (len(block.Transactions()) > 0 || len(block.Uncles()) > 0) {
 			bodiesNeeded++
 		}
 	}
@@ -1123,13 +1130,13 @@ func TestMissingHeaderAttack64Light(t *testing.T) { testMissingHeaderAttack(t, 6
 func testMissingHeaderAttack(t *testing.T, protocol int, mode SyncMode) {
 	t.Parallel()
 
-	// Create a small enough block chain to download
-	targetBlocks := blockCacheLimit - 15
-	hashes, headers, blocks, receipts := makeChain(targetBlocks, 0, genesis, nil, false)
-
 	tester := newTester()
 	defer tester.terminate()
 
+	// Create a small enough block chain to download
+	targetBlocks := blockCacheLimit - 15
+	hashes, headers, blocks, receipts := tester.makeChain(targetBlocks, 0, tester.genesis, nil, false)
+
 	// Attempt a full sync with an attacker feeding gapped headers
 	tester.newPeer("attack", protocol, hashes, headers, blocks, receipts)
 	missing := targetBlocks / 2
@@ -1156,13 +1163,13 @@ func TestShiftedHeaderAttack64Fast(t *testing.T)  { testShiftedHeaderAttack(t, 6
 func TestShiftedHeaderAttack64Light(t *testing.T) { testShiftedHeaderAttack(t, 64, LightSync) }
 
 func testShiftedHeaderAttack(t *testing.T, protocol int, mode SyncMode) {
-	// Create a small enough block chain to download
-	targetBlocks := blockCacheLimit - 15
-	hashes, headers, blocks, receipts := makeChain(targetBlocks, 0, genesis, nil, false)
-
 	tester := newTester()
 	defer tester.terminate()
 
+	// Create a small enough block chain to download
+	targetBlocks := blockCacheLimit - 15
+	hashes, headers, blocks, receipts := tester.makeChain(targetBlocks, 0, tester.genesis, nil, false)
+
 	// Attempt a full sync with an attacker feeding shifted headers
 	tester.newPeer("attack", protocol, hashes, headers, blocks, receipts)
 	delete(tester.peerHeaders["attack"], hashes[len(hashes)-2])
@@ -1188,13 +1195,13 @@ func TestInvalidHeaderRollback64Fast(t *testing.T)  { testInvalidHeaderRollback(
 func TestInvalidHeaderRollback64Light(t *testing.T) { testInvalidHeaderRollback(t, 64, LightSync) }
 
 func testInvalidHeaderRollback(t *testing.T, protocol int, mode SyncMode) {
-	// Create a small enough block chain to download
-	targetBlocks := 3*fsHeaderSafetyNet + fsMinFullBlocks
-	hashes, headers, blocks, receipts := makeChain(targetBlocks, 0, genesis, nil, false)
-
 	tester := newTester()
 	defer tester.terminate()
 
+	// Create a small enough block chain to download
+	targetBlocks := 3*fsHeaderSafetyNet + fsPivotInterval + fsMinFullBlocks
+	hashes, headers, blocks, receipts := tester.makeChain(targetBlocks, 0, tester.genesis, nil, false)
+
 	// Attempt to sync with an attacker that feeds junk during the fast sync phase.
 	// This should result in the last fsHeaderSafetyNet headers being rolled back.
 	tester.newPeer("fast-attack", protocol, hashes, headers, blocks, receipts)
@@ -1286,7 +1293,7 @@ func testHighTDStarvationAttack(t *testing.T, protocol int, mode SyncMode) {
 	tester := newTester()
 	defer tester.terminate()
 
-	hashes, headers, blocks, receipts := makeChain(0, 0, genesis, nil, false)
+	hashes, headers, blocks, receipts := tester.makeChain(0, 0, tester.genesis, nil, false)
 	tester.newPeer("attack", protocol, []common.Hash{hashes[0]}, headers, blocks, receipts)
 
 	if err := tester.sync("attack", big.NewInt(1000000), mode); err != errStallingPeer {
@@ -1333,7 +1340,7 @@ func testBlockHeaderAttackerDropping(t *testing.T, protocol int) {
 	for i, tt := range tests {
 		// Register a new peer and ensure it's presence
 		id := fmt.Sprintf("test %d", i)
-		if err := tester.newPeer(id, protocol, []common.Hash{genesis.Hash()}, nil, nil, nil); err != nil {
+		if err := tester.newPeer(id, protocol, []common.Hash{tester.genesis.Hash()}, nil, nil, nil); err != nil {
 			t.Fatalf("test %d: failed to register new peer: %v", i, err)
 		}
 		if _, ok := tester.peerHashes[id]; !ok {
@@ -1342,7 +1349,7 @@ func testBlockHeaderAttackerDropping(t *testing.T, protocol int) {
 		// Simulate a synchronisation and check the required result
 		tester.downloader.synchroniseMock = func(string, common.Hash) error { return tt.result }
 
-		tester.downloader.Synchronise(id, genesis.Hash(), big.NewInt(1000), FullSync)
+		tester.downloader.Synchronise(id, tester.genesis.Hash(), big.NewInt(1000), FullSync)
 		if _, ok := tester.peerHashes[id]; !ok != tt.drop {
 			t.Errorf("test %d: peer drop mismatch for %v: have %v, want %v", i, tt.result, !ok, tt.drop)
 		}
@@ -1361,17 +1368,17 @@ func TestSyncProgress64Light(t *testing.T) { testSyncProgress(t, 64, LightSync)
 func testSyncProgress(t *testing.T, protocol int, mode SyncMode) {
 	t.Parallel()
 
+	tester := newTester()
+	defer tester.terminate()
+
 	// Create a small enough block chain to download
 	targetBlocks := blockCacheLimit - 15
-	hashes, headers, blocks, receipts := makeChain(targetBlocks, 0, genesis, nil, false)
+	hashes, headers, blocks, receipts := tester.makeChain(targetBlocks, 0, tester.genesis, nil, false)
 
 	// Set a sync init hook to catch progress changes
 	starting := make(chan struct{})
 	progress := make(chan struct{})
 
-	tester := newTester()
-	defer tester.terminate()
-
 	tester.downloader.syncInitHook = func(origin, latest uint64) {
 		starting <- struct{}{}
 		<-progress
@@ -1434,17 +1441,17 @@ func TestForkedSyncProgress64Light(t *testing.T) { testForkedSyncProgress(t, 64,
 func testForkedSyncProgress(t *testing.T, protocol int, mode SyncMode) {
 	t.Parallel()
 
+	tester := newTester()
+	defer tester.terminate()
+
 	// Create a forked chain to simulate origin revertal
 	common, fork := MaxHashFetch, 2*MaxHashFetch
-	hashesA, hashesB, headersA, headersB, blocksA, blocksB, receiptsA, receiptsB := makeChainFork(common+fork, fork, genesis, nil, true)
+	hashesA, hashesB, headersA, headersB, blocksA, blocksB, receiptsA, receiptsB := tester.makeChainFork(common+fork, fork, tester.genesis, nil, true)
 
 	// Set a sync init hook to catch progress changes
 	starting := make(chan struct{})
 	progress := make(chan struct{})
 
-	tester := newTester()
-	defer tester.terminate()
-
 	tester.downloader.syncInitHook = func(origin, latest uint64) {
 		starting <- struct{}{}
 		<-progress
@@ -1510,17 +1517,17 @@ func TestFailedSyncProgress64Light(t *testing.T) { testFailedSyncProgress(t, 64,
 func testFailedSyncProgress(t *testing.T, protocol int, mode SyncMode) {
 	t.Parallel()
 
+	tester := newTester()
+	defer tester.terminate()
+
 	// Create a small enough block chain to download
 	targetBlocks := blockCacheLimit - 15
-	hashes, headers, blocks, receipts := makeChain(targetBlocks, 0, genesis, nil, false)
+	hashes, headers, blocks, receipts := tester.makeChain(targetBlocks, 0, tester.genesis, nil, false)
 
 	// Set a sync init hook to catch progress changes
 	starting := make(chan struct{})
 	progress := make(chan struct{})
 
-	tester := newTester()
-	defer tester.terminate()
-
 	tester.downloader.syncInitHook = func(origin, latest uint64) {
 		starting <- struct{}{}
 		<-progress
@@ -1587,17 +1594,17 @@ func TestFakedSyncProgress64Light(t *testing.T) { testFakedSyncProgress(t, 64, L
 func testFakedSyncProgress(t *testing.T, protocol int, mode SyncMode) {
 	t.Parallel()
 
+	tester := newTester()
+	defer tester.terminate()
+
 	// Create a small block chain
 	targetBlocks := blockCacheLimit - 15
-	hashes, headers, blocks, receipts := makeChain(targetBlocks+3, 0, genesis, nil, false)
+	hashes, headers, blocks, receipts := tester.makeChain(targetBlocks+3, 0, tester.genesis, nil, false)
 
 	// Set a sync init hook to catch progress changes
 	starting := make(chan struct{})
 	progress := make(chan struct{})
 
-	tester := newTester()
-	defer tester.terminate()
-
 	tester.downloader.syncInitHook = func(origin, latest uint64) {
 		starting <- struct{}{}
 		<-progress
@@ -1664,10 +1671,16 @@ func TestDeliverHeadersHang64Light(t *testing.T) { testDeliverHeadersHang(t, 64,
 
 func testDeliverHeadersHang(t *testing.T, protocol int, mode SyncMode) {
 	t.Parallel()
-	hashes, headers, blocks, receipts := makeChain(5, 0, genesis, nil, false)
+
+	master := newTester()
+	defer master.terminate()
+
+	hashes, headers, blocks, receipts := master.makeChain(5, 0, master.genesis, nil, false)
 	fakeHeads := []*types.Header{{}, {}, {}, {}}
 	for i := 0; i < 200; i++ {
 		tester := newTester()
+		tester.peerDb = master.peerDb
+
 		tester.newPeer("peer", protocol, hashes, headers, blocks, receipts)
 		// Whenever the downloader requests headers, flood it with
 		// a lot of unrequested header deliveries.
@@ -1703,44 +1716,81 @@ func testDeliverHeadersHang(t *testing.T, protocol int, mode SyncMode) {
 
 // Tests that if fast sync aborts in the critical section, it can restart a few
 // times before giving up.
-func TestFastCriticalRestarts63(t *testing.T) { testFastCriticalRestarts(t, 63) }
-func TestFastCriticalRestarts64(t *testing.T) { testFastCriticalRestarts(t, 64) }
+func TestFastCriticalRestartsFail63(t *testing.T) { testFastCriticalRestarts(t, 63, false) }
+func TestFastCriticalRestartsFail64(t *testing.T) { testFastCriticalRestarts(t, 64, false) }
+func TestFastCriticalRestartsCont63(t *testing.T) { testFastCriticalRestarts(t, 63, true) }
+func TestFastCriticalRestartsCont64(t *testing.T) { testFastCriticalRestarts(t, 64, true) }
 
-func testFastCriticalRestarts(t *testing.T, protocol int) {
-	t.Parallel()
+func testFastCriticalRestarts(t *testing.T, protocol int, progress bool) {
+	tester := newTester()
+	defer tester.terminate()
 
 	// Create a large enough blockchin to actually fast sync on
 	targetBlocks := fsMinFullBlocks + 2*fsPivotInterval - 15
-	hashes, headers, blocks, receipts := makeChain(targetBlocks, 0, genesis, nil, false)
-
-	// Create a tester peer with the critical section state roots missing (force failures)
-	tester := newTester()
-	defer tester.terminate()
+	hashes, headers, blocks, receipts := tester.makeChain(targetBlocks, 0, tester.genesis, nil, false)
 
+	// Create a tester peer with a critical section header missing (force failures)
 	tester.newPeer("peer", protocol, hashes, headers, blocks, receipts)
+	delete(tester.peerHeaders["peer"], hashes[fsMinFullBlocks-1])
+	tester.downloader.dropPeer = func(id string) {} // We reuse the same "faulty" peer throughout the test
+
+	// Remove all possible pivot state roots and slow down replies (test failure resets later)
 	for i := 0; i < fsPivotInterval; i++ {
 		tester.peerMissingStates["peer"][headers[hashes[fsMinFullBlocks+i]].Root] = true
 	}
-	tester.downloader.dropPeer = func(id string) {} // We reuse the same "faulty" peer throughout the test
+	tester.downloader.peers.peers["peer"].getNodeData = tester.peerGetNodeDataFn("peer", 500*time.Millisecond) // Enough to reach the critical section
 
 	// Synchronise with the peer a few times and make sure they fail until the retry limit
-	for i := 0; i < fsCriticalTrials; i++ {
+	for i := 0; i < int(fsCriticalTrials)-1; i++ {
 		// Attempt a sync and ensure it fails properly
 		if err := tester.sync("peer", nil, FastSync); err == nil {
 			t.Fatalf("failing fast sync succeeded: %v", err)
 		}
-		time.Sleep(100 * time.Millisecond) // Make sure no in-flight requests remain
+		time.Sleep(150 * time.Millisecond) // Make sure no in-flight requests remain
 
 		// If it's the first failure, pivot should be locked => reenable all others to detect pivot changes
 		if i == 0 {
+			if tester.downloader.fsPivotLock == nil {
+				time.Sleep(400 * time.Millisecond) // Make sure the first huge timeout expires too
+				t.Fatalf("pivot block not locked in after critical section failure")
+			}
 			tester.lock.Lock()
+			tester.peerHeaders["peer"][hashes[fsMinFullBlocks-1]] = headers[hashes[fsMinFullBlocks-1]]
 			tester.peerMissingStates["peer"] = map[common.Hash]bool{tester.downloader.fsPivotLock.Root: true}
+			tester.downloader.peers.peers["peer"].getNodeData = tester.peerGetNodeDataFn("peer", 0)
 			tester.lock.Unlock()
 		}
 	}
+	// Return all nodes if we're testing fast sync progression
+	if progress {
+		tester.lock.Lock()
+		tester.peerMissingStates["peer"] = map[common.Hash]bool{}
+		tester.lock.Unlock()
+
+		if err := tester.sync("peer", nil, FastSync); err != nil {
+			t.Fatalf("failed to synchronise blocks in progressed fast sync: %v", err)
+		}
+		time.Sleep(150 * time.Millisecond) // Make sure no in-flight requests remain
+
+		if fails := atomic.LoadUint32(&tester.downloader.fsPivotFails); fails != 1 {
+			t.Fatalf("progressed pivot trial count mismatch: have %v, want %v", fails, 1)
+		}
+		assertOwnChain(t, tester, targetBlocks+1)
+	} else {
+		if err := tester.sync("peer", nil, FastSync); err == nil {
+			t.Fatalf("succeeded to synchronise blocks in failed fast sync")
+		}
+		time.Sleep(150 * time.Millisecond) // Make sure no in-flight requests remain
+
+		if fails := atomic.LoadUint32(&tester.downloader.fsPivotFails); fails != fsCriticalTrials {
+			t.Fatalf("failed pivot trial count mismatch: have %v, want %v", fails, fsCriticalTrials)
+		}
+	}
 	// Retry limit exhausted, downloader will switch to full sync, should succeed
 	if err := tester.sync("peer", nil, FastSync); err != nil {
 		t.Fatalf("failed to synchronise blocks in slow sync: %v", err)
 	}
-	assertOwnChain(t, tester, targetBlocks+1)
+	// Note, we can't assert the chain here because the test asserter assumes sync
+	// completed using a single mode of operation, whereas fast-then-slow can result
+	// in arbitrary intermediate state that's not cleanly verifiable.
 }
diff --git a/eth/downloader/queue.go b/eth/downloader/queue.go
index fd239f7e4..b7ad92099 100644
--- a/eth/downloader/queue.go
+++ b/eth/downloader/queue.go
@@ -362,20 +362,20 @@ func (q *queue) Schedule(headers []*types.Header, from uint64) []*types.Header {
 		// Make sure chain order is honoured and preserved throughout
 		hash := header.Hash()
 		if header.Number == nil || header.Number.Uint64() != from {
-			glog.V(logger.Warn).Infof("Header #%v [%x] broke chain ordering, expected %d", header.Number, hash[:4], from)
+			glog.V(logger.Warn).Infof("Header #%v [%x…] broke chain ordering, expected %d", header.Number, hash[:4], from)
 			break
 		}
 		if q.headerHead != (common.Hash{}) && q.headerHead != header.ParentHash {
-			glog.V(logger.Warn).Infof("Header #%v [%x] broke chain ancestry", header.Number, hash[:4])
+			glog.V(logger.Warn).Infof("Header #%v [%x…] broke chain ancestry", header.Number, hash[:4])
 			break
 		}
 		// Make sure no duplicate requests are executed
 		if _, ok := q.blockTaskPool[hash]; ok {
-			glog.V(logger.Warn).Infof("Header #%d [%x] already scheduled for block fetch", header.Number.Uint64(), hash[:4])
+			glog.V(logger.Warn).Infof("Header #%d [%x…] already scheduled for block fetch", header.Number.Uint64(), hash[:4])
 			continue
 		}
 		if _, ok := q.receiptTaskPool[hash]; ok {
-			glog.V(logger.Warn).Infof("Header #%d [%x] already scheduled for receipt fetch", header.Number.Uint64(), hash[:4])
+			glog.V(logger.Warn).Infof("Header #%d [%x…] already scheduled for receipt fetch", header.Number.Uint64(), hash[:4])
 			continue
 		}
 		// Queue the header for content retrieval
@@ -388,7 +388,16 @@ func (q *queue) Schedule(headers []*types.Header, from uint64) []*types.Header {
 			q.receiptTaskQueue.Push(header, -float32(header.Number.Uint64()))
 		}
 		if q.mode == FastSync && header.Number.Uint64() == q.fastSyncPivot {
-			// Pivoting point of the fast sync, retrieve the state tries
+			// Pivoting point of the fast sync, switch the state retrieval to this
+			glog.V(logger.Debug).Infof("Switching state downloads to %d [%x…]", header.Number.Uint64(), header.Hash().Bytes()[:4])
+
+			q.stateTaskIndex = 0
+			q.stateTaskPool = make(map[common.Hash]int)
+			q.stateTaskQueue.Reset()
+			for _, req := range q.statePendPool {
+				req.Hashes = make(map[common.Hash]int) // Make sure executing requests fail, but don't disappear
+			}
+
 			q.stateSchedLock.Lock()
 			q.stateScheduler = state.NewStateSync(header.Root, q.stateDatabase)
 			q.stateSchedLock.Unlock()
@@ -866,10 +875,10 @@ func (q *queue) DeliverHeaders(id string, headers []*types.Header, headerProcCh
 	accepted := len(headers) == MaxHeaderFetch
 	if accepted {
 		if headers[0].Number.Uint64() != request.From {
-			glog.V(logger.Detail).Infof("Peer %s: first header #%v [%x] broke chain ordering, expected %d", id, headers[0].Number, headers[0].Hash().Bytes()[:4], request.From)
+			glog.V(logger.Detail).Infof("Peer %s: first header #%v [%x…] broke chain ordering, expected %d", id, headers[0].Number, headers[0].Hash().Bytes()[:4], request.From)
 			accepted = false
 		} else if headers[len(headers)-1].Hash() != target {
-			glog.V(logger.Detail).Infof("Peer %s: last header #%v [%x] broke skeleton structure, expected %x", id, headers[len(headers)-1].Number, headers[len(headers)-1].Hash().Bytes()[:4], target[:4])
+			glog.V(logger.Detail).Infof("Peer %s: last header #%v [%x…] broke skeleton structure, expected %x", id, headers[len(headers)-1].Number, headers[len(headers)-1].Hash().Bytes()[:4], target[:4])
 			accepted = false
 		}
 	}
@@ -877,12 +886,12 @@ func (q *queue) DeliverHeaders(id string, headers []*types.Header, headerProcCh
 		for i, header := range headers[1:] {
 			hash := header.Hash()
 			if want := request.From + 1 + uint64(i); header.Number.Uint64() != want {
-				glog.V(logger.Warn).Infof("Peer %s: header #%v [%x] broke chain ordering, expected %d", id, header.Number, hash[:4], want)
+				glog.V(logger.Warn).Infof("Peer %s: header #%v [%x…] broke chain ordering, expected %d", id, header.Number, hash[:4], want)
 				accepted = false
 				break
 			}
 			if headers[i].Hash() != header.ParentHash {
-				glog.V(logger.Warn).Infof("Peer %s: header #%v [%x] broke chain ancestry", id, header.Number, hash[:4])
+				glog.V(logger.Warn).Infof("Peer %s: header #%v [%x…] broke chain ancestry", id, header.Number, hash[:4])
 				accepted = false
 				break
 			}
@@ -1039,9 +1048,8 @@ func (q *queue) deliver(id string, taskPool map[common.Hash]*types.Header, taskQ
 }
 
 // DeliverNodeData injects a node state data retrieval response into the queue.
-// The method returns the number of node state entries originally requested, and
-// the number of them actually accepted from the delivery.
-func (q *queue) DeliverNodeData(id string, data [][]byte, callback func(error, int)) (int, error) {
+// The method returns the number of node state accepted from the delivery.
+func (q *queue) DeliverNodeData(id string, data [][]byte, callback func(int, bool, error)) (int, error) {
 	q.lock.Lock()
 	defer q.lock.Unlock()
 
@@ -1099,31 +1107,34 @@ func (q *queue) DeliverNodeData(id string, data [][]byte, callback func(error, i
 
 // deliverNodeData is the asynchronous node data processor that injects a batch
 // of sync results into the state scheduler.
-func (q *queue) deliverNodeData(results []trie.SyncResult, callback func(error, int)) {
+func (q *queue) deliverNodeData(results []trie.SyncResult, callback func(int, bool, error)) {
 	// Wake up WaitResults after the state has been written because it
 	// might be waiting for the pivot block state to get completed.
 	defer q.active.Signal()
 
 	// Process results one by one to permit task fetches in between
+	progressed := false
 	for i, result := range results {
 		q.stateSchedLock.Lock()
 
 		if q.stateScheduler == nil {
 			// Syncing aborted since this async delivery started, bail out
 			q.stateSchedLock.Unlock()
-			callback(errNoFetchesPending, i)
+			callback(i, progressed, errNoFetchesPending)
 			return
 		}
-		if _, err := q.stateScheduler.Process([]trie.SyncResult{result}); err != nil {
+		if prog, _, err := q.stateScheduler.Process([]trie.SyncResult{result}); err != nil {
 			// Processing a state result failed, bail out
 			q.stateSchedLock.Unlock()
-			callback(err, i)
+			callback(i, progressed, err)
 			return
+		} else if prog {
+			progressed = true
 		}
 		// Item processing succeeded, release the lock (temporarily)
 		q.stateSchedLock.Unlock()
 	}
-	callback(nil, len(results))
+	callback(len(results), progressed, nil)
 }
 
 // Prepare configures the result cache to allow accepting and caching inbound
diff --git a/trie/sync.go b/trie/sync.go
index 58b8a1fb6..2158ab750 100644
--- a/trie/sync.go
+++ b/trie/sync.go
@@ -142,34 +142,40 @@ func (s *TrieSync) Missing(max int) []common.Hash {
 	return requests
 }
 
-// Process injects a batch of retrieved trie nodes data.
-func (s *TrieSync) Process(results []SyncResult) (int, error) {
+// Process injects a batch of retrieved trie nodes data, returning if something
+// was committed to the database and also the index of an entry if processing of
+// it failed.
+func (s *TrieSync) Process(results []SyncResult) (bool, int, error) {
+	committed := false
+
 	for i, item := range results {
 		// If the item was not requested, bail out
 		request := s.requests[item.Hash]
 		if request == nil {
-			return i, ErrNotRequested
+			return committed, i, ErrNotRequested
 		}
 		// If the item is a raw entry request, commit directly
 		if request.raw {
 			request.data = item.Data
 			s.commit(request, nil)
+			committed = true
 			continue
 		}
 		// Decode the node data content and update the request
 		node, err := decodeNode(item.Hash[:], item.Data, 0)
 		if err != nil {
-			return i, err
+			return committed, i, err
 		}
 		request.data = item.Data
 
 		// Create and schedule a request for all the children nodes
 		requests, err := s.children(request, node)
 		if err != nil {
-			return i, err
+			return committed, i, err
 		}
 		if len(requests) == 0 && request.deps == 0 {
 			s.commit(request, nil)
+			committed = true
 			continue
 		}
 		request.deps += len(requests)
@@ -177,7 +183,7 @@ func (s *TrieSync) Process(results []SyncResult) (int, error) {
 			s.schedule(child)
 		}
 	}
-	return 0, nil
+	return committed, 0, nil
 }
 
 // Pending returns the number of state entries currently pending for download.
diff --git a/trie/sync_test.go b/trie/sync_test.go
index a763dc564..5292fe5cb 100644
--- a/trie/sync_test.go
+++ b/trie/sync_test.go
@@ -122,7 +122,7 @@ func testIterativeTrieSync(t *testing.T, batch int) {
 			}
 			results[i] = SyncResult{hash, data}
 		}
-		if index, err := sched.Process(results); err != nil {
+		if _, index, err := sched.Process(results); err != nil {
 			t.Fatalf("failed to process result #%d: %v", index, err)
 		}
 		queue = append(queue[:0], sched.Missing(batch)...)
@@ -152,7 +152,7 @@ func TestIterativeDelayedTrieSync(t *testing.T) {
 			}
 			results[i] = SyncResult{hash, data}
 		}
-		if index, err := sched.Process(results); err != nil {
+		if _, index, err := sched.Process(results); err != nil {
 			t.Fatalf("failed to process result #%d: %v", index, err)
 		}
 		queue = append(queue[len(results):], sched.Missing(10000)...)
@@ -190,7 +190,7 @@ func testIterativeRandomTrieSync(t *testing.T, batch int) {
 			results = append(results, SyncResult{hash, data})
 		}
 		// Feed the retrieved results back and queue new tasks
-		if index, err := sched.Process(results); err != nil {
+		if _, index, err := sched.Process(results); err != nil {
 			t.Fatalf("failed to process result #%d: %v", index, err)
 		}
 		queue = make(map[common.Hash]struct{})
@@ -231,7 +231,7 @@ func TestIterativeRandomDelayedTrieSync(t *testing.T) {
 			}
 		}
 		// Feed the retrieved results back and queue new tasks
-		if index, err := sched.Process(results); err != nil {
+		if _, index, err := sched.Process(results); err != nil {
 			t.Fatalf("failed to process result #%d: %v", index, err)
 		}
 		for _, result := range results {
@@ -272,7 +272,7 @@ func TestDuplicateAvoidanceTrieSync(t *testing.T) {
 
 			results[i] = SyncResult{hash, data}
 		}
-		if index, err := sched.Process(results); err != nil {
+		if _, index, err := sched.Process(results); err != nil {
 			t.Fatalf("failed to process result #%d: %v", index, err)
 		}
 		queue = append(queue[:0], sched.Missing(0)...)
@@ -304,7 +304,7 @@ func TestIncompleteTrieSync(t *testing.T) {
 			results[i] = SyncResult{hash, data}
 		}
 		// Process each of the trie nodes
-		if index, err := sched.Process(results); err != nil {
+		if _, index, err := sched.Process(results); err != nil {
 			t.Fatalf("failed to process result #%d: %v", index, err)
 		}
 		for _, result := range results {