Optimize merge tracker and add merge metrics

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

@@ -13,7 +13,7 @@ import {
 } from "@lodestar/state-transition";
 import {IBeaconConfig} from "@lodestar/config";
 import {allForks, UintNum64, Root, phase0, Slot, RootHex, Epoch, ValidatorIndex} from "@lodestar/types";
-import {CheckpointWithHex, IForkChoice, ProtoBlock} from "@lodestar/fork-choice";
+import {CheckpointWithHex, ExecutionStatus, IForkChoice, ProtoBlock} from "@lodestar/fork-choice";
 import {ILogger, toHex} from "@lodestar/utils";
 import {CompositeTypeAny, fromHexString, TreeView, Type} from "@chainsafe/ssz";
 import {GENESIS_EPOCH, ZERO_HASH} from "../constants/index.js";
@@ -521,6 +521,17 @@ export class BeaconChain implements IBeaconChain {
     this.seenAggregatedAttestations.prune(epoch);
     this.seenBlockAttesters.prune(epoch);
     this.beaconProposerCache.prune(epoch);
+
+    // Poll for merge block in the background to speed-up block production. Only if:
+    // - after BELLATRIX_FORK_EPOCH
+    // - Beacon node synced
+    // - head state not isMergeTransitionComplete
+    if (this.config.BELLATRIX_FORK_EPOCH - epoch < 1) {
+      const head = this.forkChoice.getHead();
+      if (epoch - computeEpochAtSlot(head.slot) < 5 && head.executionStatus === ExecutionStatus.PreMerge) {
+        this.eth1.startPollingMergeBlock();
+      }
+    }
   }
 
   private onForkChoiceHead(head: ProtoBlock): void {

packages/beacon-node/src/chain/factory/block/body.ts

@@ -183,7 +183,7 @@ export async function prepareExecutionPayload(
   state: CachedBeaconStateBellatrix,
   suggestedFeeRecipient: string
 ): Promise<{isPremerge: true} | {isPremerge: false; payloadId: PayloadId}> {
-  const parentHashRes = getExecutionPayloadParentHash(chain, state);
+  const parentHashRes = await getExecutionPayloadParentHash(chain, state);
   if (parentHashRes.isPremerge) {
     // Return null only if the execution is pre-merge
     return {isPremerge: true};
@@ -237,7 +237,7 @@ async function prepareExecutionPayloadHeader(
     throw Error("executionBuilder required");
   }
 
-  const parentHashRes = getExecutionPayloadParentHash(chain, state);
+  const parentHashRes = await getExecutionPayloadParentHash(chain, state);
 
   if (parentHashRes.isPremerge) {
     // TODO: Is this okay?
@@ -248,13 +248,13 @@ async function prepareExecutionPayloadHeader(
   return chain.executionBuilder.getPayloadHeader(state.slot, parentHash, proposerPubKey);
 }
 
-function getExecutionPayloadParentHash(
+async function getExecutionPayloadParentHash(
   chain: {
     eth1: IEth1ForBlockProduction;
     config: IChainForkConfig;
   },
   state: CachedBeaconStateBellatrix
-): {isPremerge: true} | {isPremerge: false; parentHash: Root} {
+): Promise<{isPremerge: true} | {isPremerge: false; parentHash: Root}> {
   // Use different POW block hash parent for block production based on merge status.
   // Returned value of null == using an empty ExecutionPayload value
   if (isMergeTransitionComplete(state)) {
@@ -271,7 +271,7 @@ function getExecutionPayloadParentHash(
         }, actual: ${getCurrentEpoch(state)}`
       );
 
-    const terminalPowBlockHash = chain.eth1.getTerminalPowBlock();
+    const terminalPowBlockHash = await chain.eth1.getTerminalPowBlock();
     if (terminalPowBlockHash === null) {
       // Pre-merge, no prepare payload call is needed
       return {isPremerge: true};