[ETCM-763] [ETCM-819] improve fast sync stability (#1001)

Co-authored-by: Anastasiia Pushkina <[email protected]>

Author: jvdp

src/it/scala/io/iohk/ethereum/sync/FastSyncItSpec.scala

@@ -24,7 +24,7 @@ class FastSyncItSpec extends FlatSpecBase with Matchers with BeforeAndAfterAll {
     testScheduler.awaitTermination(60.second)
   }
 
-  "FastSync" should "sync blockchain without state nodes" in customTestCaseResourceM(
+  it should "sync blockchain without state nodes" in customTestCaseResourceM(
     FakePeer.start3FakePeersRes()
   ) { case (peer1, peer2, peer3) =>
     for {
@@ -228,8 +228,8 @@ class FastSyncItSpec extends FlatSpecBase with Matchers with BeforeAndAfterAll {
 
       _ <- peer4.importBlocksUntil(1100)(IdentityUpdate)
 
-      _ <- peer1.connectToPeers(Set(peer2.node, peer3.node, peer4.node))
-      _ <- peer1.startFastSync().delayExecution(50.milliseconds)
+      _ <- peer1.connectToPeers(Set(peer2.node, peer3.node, peer4.node)).delayExecution(5.seconds)
+      _ <- peer1.startFastSync().delayExecution(50.millis)
       _ <- peer2.importBlocksUntil(1200)(IdentityUpdate)
       _ <- peer1.waitForFastSyncFinish()
     } yield {

src/it/scala/io/iohk/ethereum/sync/util/CommonFakePeer.scala

@@ -27,7 +27,15 @@ import io.iohk.ethereum.network.handshaker.{EtcHandshaker, EtcHandshakerConfigur
 import io.iohk.ethereum.network.p2p.EthereumMessageDecoder
 import io.iohk.ethereum.network.rlpx.AuthHandshaker
 import io.iohk.ethereum.network.rlpx.RLPxConnectionHandler.RLPxConfiguration
-import io.iohk.ethereum.network.{EtcPeerManagerActor, ForkResolver, KnownNodesManager, PeerEventBusActor, PeerManagerActor, PeerStatisticsActor, ServerActor}
+import io.iohk.ethereum.network.{
+  EtcPeerManagerActor,
+  ForkResolver,
+  KnownNodesManager,
+  PeerEventBusActor,
+  PeerManagerActor,
+  PeerStatisticsActor,
+  ServerActor
+}
 import io.iohk.ethereum.nodebuilder.PruningConfigBuilder
 import io.iohk.ethereum.sync.util.SyncCommonItSpec._
 import io.iohk.ethereum.sync.util.SyncCommonItSpecUtils._

src/it/scala/io/iohk/ethereum/sync/util/RegularSyncItSpecUtils.scala

@@ -67,7 +67,10 @@ object RegularSyncItSpecUtils {
 
     lazy val checkpointBlockGenerator: CheckpointBlockGenerator = new CheckpointBlockGenerator
     lazy val peersClient: ActorRef =
-      system.actorOf(PeersClient.props(etcPeerManager, peerEventBus, blacklist, testSyncConfig, system.scheduler), "peers-client")
+      system.actorOf(
+        PeersClient.props(etcPeerManager, peerEventBus, blacklist, testSyncConfig, system.scheduler),
+        "peers-client"
+      )
 
     lazy val ledger: Ledger =
       new LedgerImpl(bl, blockchainConfig, syncConfig, buildEthashConsensus(), Scheduler.global)
@@ -83,7 +86,14 @@ object RegularSyncItSpecUtils {
 
     val broadcasterRef: ActorRef = system.actorOf(
       BlockBroadcasterActor
-        .props(new BlockBroadcast(etcPeerManager), peerEventBus, etcPeerManager, blacklist, syncConfig, system.scheduler),
+        .props(
+          new BlockBroadcast(etcPeerManager),
+          peerEventBus,
+          etcPeerManager,
+          blacklist,
+          syncConfig,
+          system.scheduler
+        ),
       "block-broadcaster"
     )
 

src/it/scala/io/iohk/ethereum/txExecTest/ForksTest.scala

@@ -50,7 +50,7 @@ class ForksTest extends AnyFlatSpec with Matchers {
       daoForkConfig = None,
       gasTieBreaker = false,
       ethCompatibleStorage = true,
-      treasuryAddress = Address(0),
+      treasuryAddress = Address(0)
     )
 
     val noErrors = a[Right[_, Seq[Receipt]]]

src/main/scala/io/iohk/ethereum/blockchain/sync/fast/FastSync.scala

@@ -41,6 +41,7 @@ import scala.util.Random
 import scala.collection.mutable
 import scala.util.Try
 import scala.util.Success
+import java.util.concurrent.atomic.AtomicInteger
 
 // scalastyle:off file.size.limit
 class FastSync(
@@ -115,8 +116,11 @@ class FastSync(
       }
   }
 
+  private val actorCounter = new AtomicInteger
+  private def countActor: Int = actorCounter.incrementAndGet
+
   // scalastyle:off number.of.methods
-  private class SyncingHandler(initialSyncState: SyncState) {
+  private class SyncingHandler(initialSyncState: SyncState, var masterPeer: Option[Peer] = None) {
 
     //not part of syncstate as we do not want to persist is.
     private var stateSyncRestartRequested = false
@@ -128,7 +132,6 @@ class FastSync(
     private var assignedHandlers: Map[ActorRef, Peer] = Map.empty
     private var peerRequestsTime: Map[Peer, Instant] = Map.empty
 
-    private var masterPeer: Option[Peer] = None
     // TODO ETCM-701 get rid of state and move skeleton download to a separate actor
     private val blockHeadersQueue: mutable.Queue[HeaderRange] = mutable.Queue.empty
     private var currentSkeletonState: Option[HeaderSkeleton] = None
@@ -138,13 +141,13 @@ class FastSync(
     private var requestedBlockBodies: Map[ActorRef, Seq[ByteString]] = Map.empty
     private var requestedReceipts: Map[ActorRef, Seq[ByteString]] = Map.empty
 
-    private val syncStateStorageActor = context.actorOf(Props[StateStorageActor](), "state-storage")
+    private val syncStateStorageActor = context.actorOf(Props[StateStorageActor](), s"$countActor-state-storage")
     syncStateStorageActor ! fastSyncStateStorage
 
     private val branchResolver = context.actorOf(
       FastSyncBranchResolverActor
         .props(self, peerEventBus, etcPeerManager, blockchain, blacklist, syncConfig, appStateStorage, scheduler),
-      "fast-sync-branch-resolver"
+      s"$countActor-fast-sync-branch-resolver"
     )
 
     private val syncStateScheduler = context.actorOf(
@@ -157,7 +160,7 @@ class FastSync(
           blacklist,
           scheduler
         ),
-      "state-scheduler"
+      s"$countActor-state-scheduler"
     )
 
     //Delay before starting to persist snapshot. It should be 0, as the presence of it marks that fast sync was started
@@ -178,7 +181,7 @@ class FastSync(
         syncState = syncState.copy(downloadedNodesCount = saved, totalNodesCount = saved + missing)
     }
 
-    def receive: Receive = handlePeerListMessages orElse handleStatus orElse {
+    def receive: Receive = handlePeerListMessages orElse handleStatus orElse handleRequestFailure orElse {
       case UpdatePivotBlock(reason) => updatePivotBlock(reason)
       case WaitingForNewTargetBlock =>
         log.info("State sync stopped until receiving new pivot block")
@@ -190,10 +193,15 @@ class FastSync(
       case StateSyncFinished =>
         syncState = syncState.copy(stateSyncFinished = true)
         processSyncing()
+    }
+
+    def handleRequestFailure: Receive = {
       case PeerRequestHandler.RequestFailed(peer, reason) =>
         handleRequestFailure(peer, sender(), FastSyncRequestFailed(reason))
-      case Terminated(ref) if assignedHandlers.contains(ref) =>
-        handleRequestFailure(assignedHandlers(ref), ref, PeerActorTerminated)
+      case Terminated(ref) =>
+        assignedHandlers.get(ref).foreach {
+          handleRequestFailure(_, ref, PeerActorTerminated)
+        }
     }
 
     // TODO ETCM-701 will be moved to separate actor and refactored
@@ -340,12 +348,13 @@ class FastSync(
         batchFailuresCount += 1
         if (batchFailuresCount > fastSyncMaxBatchRetries) {
           log.info("Max number of allowed failures reached. Switching branch and master peer.")
-          handleRewind(header, masterPeer.get, fastSyncBlockValidationN, blacklistDuration)
+
+          blockHeadersQueue.dequeueAll(_ => true)
+
+          handleRewind(header, masterPeer.get, fastSyncBlockValidationN, blacklistDuration, continueSyncing = false)
 
           // Start branch resolution and wait for response from the FastSyncBranchResolver actor.
           context become waitingForBranchResolution
-          currentSkeletonState = None
-          blockHeadersQueue.dequeueAll(_ => true)
           branchResolver ! FastSyncBranchResolverActor.StartBranchResolver
         }
       }
@@ -362,19 +371,33 @@ class FastSync(
       }
     }
 
-    private def waitingForBranchResolution: Receive = handleStatus orElse {
+    private def waitingForBranchResolution: Receive = handleStatus orElse handleRequestFailure orElse {
       case FastSyncBranchResolverActor.BranchResolvedSuccessful(firstCommonBlockNumber, newMasterPeer) =>
+        log.debug(
+          s"Resolved branch with first common block number $firstCommonBlockNumber for new master peer $newMasterPeer"
+        )
         // Reset the batch failures count
         batchFailuresCount = 0
 
+        context.children.foreach { child =>
+          log.debug(s"Unwatching and killing $child")
+          context.unwatch(child)
+          child ! PoisonPill
+        }
+
         // Restart syncing from the valid block available in state.
-        syncState = syncState.copy(
-          bestBlockHeaderNumber = firstCommonBlockNumber,
-          nextBlockToFullyValidate = firstCommonBlockNumber + 1
+        log.debug("Starting with fresh SyncingHandler")
+        val syncingHandler = new SyncingHandler(
+          syncState.copy(
+            bestBlockHeaderNumber = firstCommonBlockNumber,
+            nextBlockToFullyValidate = firstCommonBlockNumber + 1,
+            pivotBlockUpdateFailures = 0
+          ),
+          masterPeer = Some(newMasterPeer)
         )
-        masterPeer = Some(newMasterPeer)
-        context become receive
-        processSyncing()
+        context.become(syncingHandler.receive)
+        syncingHandler.processSyncing()
+
       case _: FastSyncBranchResolverActor.BranchResolutionFailed =>
         // there isn't much we can do if we don't find a branch/peer to continue syncing, so let's try again
         branchResolver ! FastSyncBranchResolverActor.StartBranchResolver
@@ -390,7 +413,8 @@ class FastSync(
       log.info("Asking for new pivot block")
       val pivotBlockSelector = {
         context.actorOf(
-          PivotBlockSelector.props(etcPeerManager, peerEventBus, syncConfig, scheduler, context.self, blacklist)
+          PivotBlockSelector.props(etcPeerManager, peerEventBus, syncConfig, scheduler, context.self, blacklist),
+          s"$countActor-pivot-block-selector-update"
         )
       }
       pivotBlockSelector ! PivotBlockSelector.SelectPivotBlock
@@ -408,7 +432,7 @@ class FastSync(
     }
 
     def waitingForPivotBlockUpdate(updateReason: PivotBlockUpdateReason): Receive =
-      handlePeerListMessages orElse handleStatus orElse {
+      handlePeerListMessages orElse handleStatus orElse handleRequestFailure orElse {
         case PivotBlockSelector.Result(pivotBlockHeader)
             if newPivotIsGoodEnough(pivotBlockHeader, syncState, updateReason) =>
           log.info("New pivot block with number {} received", pivotBlockHeader.number)
@@ -507,7 +531,9 @@ class FastSync(
       }
 
     private def removeRequestHandler(handler: ActorRef): Unit = {
+      log.debug(s"Removing request handler ${handler.path}")
       context unwatch handler
+      skeletonHandler = skeletonHandler.filter(_ != handler)
       assignedHandlers -= handler
     }
 
@@ -560,17 +586,23 @@ class FastSync(
       syncState = syncState.updateNextBlockToValidate(header, K, X)
     }
 
-    private def handleRewind(header: BlockHeader, peer: Peer, N: Int, duration: FiniteDuration): Unit = {
+    private def handleRewind(
+        header: BlockHeader,
+        peer: Peer,
+        N: Int,
+        duration: FiniteDuration,
+        continueSyncing: Boolean = true
+    ): Unit = {
       blacklist.add(peer.id, duration, BlockHeaderValidationFailed)
       if (header.number <= syncState.safeDownloadTarget) {
         discardLastBlocks(header.number, N)
         syncState = syncState.updateDiscardedBlocks(header, N)
         if (header.number >= syncState.pivotBlock.number) {
           updatePivotBlock(LastBlockValidationFailed)
-        } else {
+        } else if (continueSyncing) {
           processSyncing()
         }
-      } else {
+      } else if (continueSyncing) {
         processSyncing()
       }
     }
@@ -685,6 +717,9 @@ class FastSync(
     }
 
     private def handleRequestFailure(peer: Peer, handler: ActorRef, reason: BlacklistReason): Unit = {
+      if (skeletonHandler == Some(handler))
+        currentSkeletonState = None
+
       removeRequestHandler(handler)
 
       requestedHeaders.get(peer).foreach(blockHeadersQueue.enqueue)
@@ -816,6 +851,16 @@ class FastSync(
 
     def processSyncing(): Unit = {
       FastSyncMetrics.measure(syncState)
+      log.debug(
+        "Start of processSyncing: {}",
+        Map(
+          "fullySynced" -> fullySynced,
+          "blockchainDataToDownload" -> blockchainDataToDownload,
+          "noBlockchainWorkRemaining" -> noBlockchainWorkRemaining,
+          "stateSyncFinished" -> syncState.stateSyncFinished,
+          "notInTheMiddleOfUpdate" -> notInTheMiddleOfUpdate
+        )
+      )
       if (fullySynced) {
         finish()
       } else {
@@ -887,8 +932,9 @@ class FastSync(
         requestSkeletonHeaders(peer)
       } else {
         log.debug(
-          "Nothing to request. Waiting for responses for [{}] sent requests.",
-          assignedHandlers.size + skeletonHandler.size
+          "Nothing to request. Waiting for responses from: {} and/or {}",
+          assignedHandlers.keys,
+          skeletonHandler
         )
       }
     }
@@ -911,7 +957,8 @@ class FastSync(
           peerEventBus,
           requestMsg = GetReceipts(receiptsToGet),
           responseMsgCode = Codes.ReceiptsCode
-        )
+        ),
+        s"$countActor-peer-request-handler-receipts"
       )
 
       context watch handler
@@ -934,7 +981,8 @@ class FastSync(
           peerEventBus,
           requestMsg = GetBlockBodies(blockBodiesToGet),
           responseMsgCode = Codes.BlockBodiesCode
-        )
+        ),
+        s"$countActor-peer-request-handler-block-bodies"
       )
 
       context watch handler
@@ -962,7 +1010,8 @@ class FastSync(
               peerEventBus,
               requestMsg = GetBlockHeaders(Left(toRequest.from), toRequest.limit, skip = 0, reverse = false),
               responseMsgCode = Codes.BlockHeadersCode
-            )
+            ),
+            s"$countActor-peer-request-handler-block-headers"
           )
 
           context watch handler
@@ -1026,7 +1075,8 @@ class FastSync(
               peerEventBus,
               requestMsg = msg,
               responseMsgCode = Codes.BlockHeadersCode
-            )
+            ),
+            s"$countActor-peer-request-handler-block-headers-skeleton"
           )
 
           context watch handler

src/main/scala/io/iohk/ethereum/blockchain/sync/fast/FastSyncBranchResolverActor.scala

@@ -47,7 +47,13 @@ class FastSyncBranchResolverActor(
 
   private def waitingForPeerWithHighestBlock: Receive = handlePeerListMessages orElse { case StartBranchResolver =>
     getPeerWithHighestBlock match {
-      case Some(PeerWithInfo(peer, _)) => requestRecentBlockHeaders(peer, blockchain.getBestBlockNumber())
+      case Some(peerWithInfo @ PeerWithInfo(peer, _)) =>
+        log.debug(
+          "Starting branch resolution now with peer {} and block number {}",
+          peerWithInfo,
+          blockchain.getBestBlockNumber()
+        )
+        requestRecentBlockHeaders(peer, blockchain.getBestBlockNumber())
       case None =>
         log.info("Waiting for peers, rescheduling StartBranchResolver")
         timers.startSingleTimer(RestartTimerKey, StartBranchResolver, 1.second)

src/main/scala/io/iohk/ethereum/blockchain/sync/fast/PivotBlockSelector.scala

@@ -71,7 +71,7 @@ class PivotBlockSelector(
     } else {
       log.info(
         "Cannot pick pivot block. Need at least {} peers, but there are only {} which meet the criteria " +
-          "({} all available at the moment).",
+          "({} all available at the moment). Best block number = {}",
         minPeersToChoosePivotBlock,
         correctPeers.size,
         peersToDownloadFrom.size,