test: fix flaky sim tests

packages/beacon-node/src/sync/options.ts

@@ -1,3 +1,5 @@
+import {SLOTS_PER_EPOCH} from "@lodestar/params";
+
 export type SyncOptions = {
   /**
    * Allow node to consider itself synced without being connected to a peer.
@@ -22,11 +24,22 @@ export type SyncOptions = {
   backfillBatchSize: number;
   /** For testing only, MAX_PENDING_BLOCKS by default */
   maxPendingBlocks?: number;
+
+  /**
+   * The number of slots ahead of us that is allowed before starting a RangeSync
+   * If a peer is within this tolerance (forwards or backwards), it is treated as a fully sync'd peer.
+   *
+   * This means that we consider ourselves synced (and hence subscribe to all subnets and block
+   * gossip if no peers are further than this range ahead of us that we have not already downloaded
+   * blocks for.
+   */
+  slotImportTolerance?: number;
 };
 
 export const defaultSyncOptions: SyncOptions = {
   isSingleNode: false,
   disableProcessAsChainSegment: false,
   /** By default skip the backfill sync */
   backfillBatchSize: 0,
+  slotImportTolerance: SLOTS_PER_EPOCH,
 };

packages/beacon-node/src/sync/sync.ts

@@ -28,15 +28,6 @@ export class BeaconSync implements IBeaconSync {
 
   /** For metrics only */
   private readonly peerSyncType = new Map<string, PeerSyncType>();
-
-  /**
-   * The number of slots ahead of us that is allowed before starting a RangeSync
-   * If a peer is within this tolerance (forwards or backwards), it is treated as a fully sync'd peer.
-   *
-   * This means that we consider ourselves synced (and hence subscribe to all subnets and block
-   * gossip if no peers are further than this range ahead of us that we have not already downloaded
-   * blocks for.
-   */
   private readonly slotImportTolerance: Slot;
 
   constructor(opts: SyncOptions, modules: SyncModules) {
@@ -48,7 +39,7 @@ export class BeaconSync implements IBeaconSync {
     this.logger = logger;
     this.rangeSync = new RangeSync(modules, opts);
     this.unknownBlockSync = new UnknownBlockSync(config, network, chain, logger, metrics, opts);
-    this.slotImportTolerance = SLOTS_PER_EPOCH;
+    this.slotImportTolerance = opts.slotImportTolerance ?? SLOTS_PER_EPOCH;
 
     // Subscribe to RangeSync completing a SyncChain and recompute sync state
     if (!opts.disableRangeSync) {
@@ -241,7 +232,7 @@ export class BeaconSync implements IBeaconSync {
       }
     }
 
-    // If we stopped being synced and falled significantly behind, stop gossip
+    // If we stopped being synced and fallen significantly behind, stop gossip
     else if (state !== SyncState.Synced) {
       const syncDiff = this.chain.clock.currentSlot - this.chain.forkChoice.getHead().slot;
       if (syncDiff > this.slotImportTolerance * 2) {

packages/cli/src/options/beaconNodeOptions/sync.ts

@@ -6,6 +6,7 @@ export type SyncArgs = {
   "sync.disableProcessAsChainSegment"?: boolean;
   "sync.disableRangeSync"?: boolean;
   "sync.backfillBatchSize"?: number;
+  "sync.slotImportTolerance"?: number;
 };
 
 export function parseArgs(args: SyncArgs): IBeaconNodeOptions["sync"] {
@@ -14,6 +15,7 @@ export function parseArgs(args: SyncArgs): IBeaconNodeOptions["sync"] {
     disableProcessAsChainSegment: args["sync.disableProcessAsChainSegment"],
     backfillBatchSize: args["sync.backfillBatchSize"] ?? defaultOptions.sync.backfillBatchSize,
     disableRangeSync: args["sync.disableRangeSync"],
+    slotImportTolerance: args["sync.slotImportTolerance"] ?? defaultOptions.sync.slotImportTolerance,
   };
 }
 
@@ -36,6 +38,14 @@ Use only for local networks with a single node, can be dangerous in regular netw
     group: "sync",
   },
 
+  "sync.slotImportTolerance": {
+    hidden: true,
+    type: "number",
+    description: "Number of slot tolerance to trigger range sync and to measure if node is synced.",
+    defaultDescription: String(defaultOptions.sync.slotImportTolerance),
+    group: "sync",
+  },
+
   "sync.disableProcessAsChainSegment": {
     hidden: true,
     type: "boolean",

packages/cli/test/sim/multi_fork.test.ts

@@ -199,19 +199,29 @@ await checkpointSync.execution.job.stop();
 
 // Unknown block sync
 // ========================================================
+const headForUnknownBlockSync = await env.nodes[0].beacon.api.beacon.getBlockV2("head");
+ApiError.assert(headForUnknownBlockSync);
 const unknownBlockSync = await env.createNodePair({
   id: "unknown-block-sync-node",
   beacon: {
     type: BeaconClient.Lodestar,
-    options: {clientOptions: {"network.allowPublishToZeroPeers": true, "sync.disableRangeSync": true}},
+    options: {
+      clientOptions: {
+        "network.allowPublishToZeroPeers": true,
+        "sync.disableRangeSync": true,
+        // unknownBlockSync node start when other nodes are multiple epoch ahead and
+        // unknown block sync can work only if the gap is maximum `slotImportTolerance * 2`
+        // default value for slotImportTolerance is one epoch, so if gap is more than 2 epoch
+        // unknown block sync will not work. So why we have to increase it for tests.
+        "sync.slotImportTolerance": headForUnknownBlockSync.response.data.message.slot / 2 + 2,
+      },
+    },
   },
   execution: ExecutionClient.Geth,
   keysCount: 0,
 });
 await unknownBlockSync.execution.job.start();
 await unknownBlockSync.beacon.job.start();
-const headForUnknownBlockSync = await env.nodes[0].beacon.api.beacon.getBlockV2("head");
-ApiError.assert(headForUnknownBlockSync);
 await connectNewNode(unknownBlockSync, env.nodes);
 
 // Wait for EL node to start and sync

packages/cli/test/unit/options/beaconNodeOptions.test.ts

@@ -206,6 +206,7 @@ describe("options / beaconNodeOptions", () => {
       },
       sync: {
         isSingleNode: true,
+        slotImportTolerance: 32,
         disableProcessAsChainSegment: true,
         backfillBatchSize: 64,
         disableRangeSync: false,