feat: track performance of processFinalizedCheckpoint() (#8530)

**Motivation**

- investigate and maintain the performance of
`processFinalizedCheckpoint()`
- this is part of #8526

**Description**

- track duration of `processFinalizedCheckpoint()` by tasks, the result
on a hoodi node, it shows that `FrequencyStateArchiveStrategy` takes the
most time

<img width="941" height="297" alt="Screenshot 2025-10-14 at 13 45 38"
src="https://github.com/user-attachments/assets/ef440399-538b-4a4a-a63c-e775745b25e6"
/>


- track different steps of `FrequencyStateArchiveStrategy`, the result
shows that the mainthread is blocked by different db queries cc
@wemeetagain

<img width="1291" height="657" alt="Screenshot 2025-10-14 at 13 46 36"
src="https://github.com/user-attachments/assets/3b19f008-c7d8-49a4-9dc5-e68b1a5ba2a5"
/>

part of #8526

---------

Co-authored-by: Tuyen Nguyen <twoeths@users.noreply.github.com>

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

@@ -25,6 +25,16 @@ type ArchiveStoreModules = {
 
 type ArchiveStoreInitOpts = ArchiveStoreOpts & {dbName: string; anchorState: {finalizedCheckpoint: Checkpoint}};
 
+export enum ArchiveStoreTask {
+  ArchiveBlocks = "archive_blocks",
+  PruneHistory = "prune_history",
+  OnFinalizedCheckpoint = "on_finalized_checkpoint",
+  MaybeArchiveState = "maybe_archive_state",
+  RegenPruneOnFinalized = "regen_prune_on_finalized",
+  ForkchoicePrune = "forkchoice_prune",
+  UpdateBackfillRange = "update_backfill_range",
+}
+
 /**
  * Used for running tasks that depends on some events or are executed
  * periodically.
@@ -176,6 +186,8 @@ export class ArchiveStore {
     try {
       const finalizedEpoch = finalized.epoch;
       this.logger.verbose("Start processing finalized checkpoint", {epoch: finalizedEpoch, rootHex: finalized.rootHex});
+
+      let timer = this.metrics?.processFinalizedCheckpoint.durationByTask.startTimer();
       await archiveBlocks(
         this.chain.config,
         this.db,
@@ -188,7 +200,10 @@ export class ArchiveStore {
         this.chain.opts.persistOrphanedBlocks,
         this.chain.opts.persistOrphanedBlocksDir
       );
+      timer?.({source: ArchiveStoreTask.ArchiveBlocks});
+
       if (this.opts.pruneHistory) {
+        timer = this.metrics?.processFinalizedCheckpoint.durationByTask.startTimer();
         await pruneHistory(
           this.chain.config,
           this.db,
@@ -197,18 +212,30 @@ export class ArchiveStore {
           finalizedEpoch,
           this.chain.clock.currentEpoch
         );
+        timer?.({source: ArchiveStoreTask.PruneHistory});
       }
 
+      timer = this.metrics?.processFinalizedCheckpoint.durationByTask.startTimer();
       await this.statesArchiverStrategy.onFinalizedCheckpoint(finalized, this.metrics);
+      timer?.({source: ArchiveStoreTask.OnFinalizedCheckpoint});
 
       // should be after ArchiveBlocksTask to handle restart cleanly
+      timer = this.metrics?.processFinalizedCheckpoint.durationByTask.startTimer();
       await this.statesArchiverStrategy.maybeArchiveState(finalized, this.metrics);
+      timer?.({source: ArchiveStoreTask.MaybeArchiveState});
 
+      timer = this.metrics?.processFinalizedCheckpoint.durationByTask.startTimer();
       this.chain.regen.pruneOnFinalized(finalizedEpoch);
+      timer?.({source: ArchiveStoreTask.RegenPruneOnFinalized});
 
       // tasks rely on extended fork choice
+      timer = this.metrics?.processFinalizedCheckpoint.durationByTask.startTimer();
       const prunedBlocks = this.chain.forkChoice.prune(finalized.rootHex);
+      timer?.({source: ArchiveStoreTask.ForkchoicePrune});
+
+      timer = this.metrics?.processFinalizedCheckpoint.durationByTask.startTimer();
       await updateBackfillRange({chain: this.chain, db: this.db, logger: this.logger}, finalized);
+      timer?.({source: ArchiveStoreTask.UpdateBackfillRange});
 
       this.logger.verbose("Finish processing finalized checkpoint", {
         epoch: finalizedEpoch,

packages/beacon-node/src/chain/archiveStore/strategies/frequencyStateArchiveStrategy.ts

@@ -17,6 +17,15 @@ import {StateArchiveStrategy, StatesArchiveOpts} from "../interface.js";
  */
 export const PERSIST_TEMP_STATE_EVERY_EPOCHS = 32;
 
+export enum FrequencyStateArchiveStep {
+  LoadLastStoredSlot = "load_last_stored_slot",
+  GetFinalizedState = "get_finalized_state",
+  // SerializeState is tracked via stateSerializeDuration metric
+  PersistState = "persist_state",
+  LoadStoredSlotsToDelete = "load_stored_slots_to_delete",
+  DeleteOldStates = "delete_old_states",
+}
+
 /**
  * Archives finalized states from active bucket to archive bucket.
  *
@@ -47,7 +56,10 @@ export class FrequencyStateArchiveStrategy implements StateArchiveStrategy {
    * ```
    */
   async maybeArchiveState(finalized: CheckpointWithHex, metrics?: Metrics | null): Promise<void> {
+    let timer = metrics?.processFinalizedCheckpoint.frequencyStateArchive.startTimer();
     const lastStoredSlot = await this.db.stateArchive.lastKey();
+    timer?.({step: FrequencyStateArchiveStep.LoadLastStoredSlot});
+
     const lastStoredEpoch = computeEpochAtSlot(lastStoredSlot ?? 0);
     const {archiveStateEpochFrequency} = this.opts;
 
@@ -60,15 +72,19 @@ export class FrequencyStateArchiveStrategy implements StateArchiveStrategy {
         (Math.floor(finalized.epoch / archiveStateEpochFrequency) - 1) * archiveStateEpochFrequency
       );
 
+      timer = metrics?.processFinalizedCheckpoint.frequencyStateArchive.startTimer();
       const storedStateSlots = await this.db.stateArchive.keys({
         lt: computeStartSlotAtEpoch(finalized.epoch),
         gte: computeStartSlotAtEpoch(minEpoch),
       });
+      timer?.({step: FrequencyStateArchiveStep.LoadStoredSlotsToDelete});
 
       const statesSlotsToDelete = computeStateSlotsToDelete(storedStateSlots, archiveStateEpochFrequency);
+      timer = metrics?.processFinalizedCheckpoint.frequencyStateArchive.startTimer();
       if (statesSlotsToDelete.length > 0) {
         await this.db.stateArchive.batchDelete(statesSlotsToDelete);
       }
+      timer?.({step: FrequencyStateArchiveStep.DeleteOldStates});
 
       // More logs to investigate the rss spike issue https://github.com/ChainSafe/lodestar/issues/5591
       this.logger.verbose("Archived state completed", {
@@ -86,24 +102,31 @@ export class FrequencyStateArchiveStrategy implements StateArchiveStrategy {
    */
   async archiveState(finalized: CheckpointWithHex, metrics?: Metrics | null): Promise<void> {
     // starting from Mar 2024, the finalized state could be from disk or in memory
+    let timer = metrics?.processFinalizedCheckpoint.frequencyStateArchive.startTimer();
     const finalizedStateOrBytes = await this.regen.getCheckpointStateOrBytes(finalized);
+    timer?.({step: FrequencyStateArchiveStep.GetFinalizedState});
+
     const {rootHex} = finalized;
     if (!finalizedStateOrBytes) {
       throw Error(`No state in cache for finalized checkpoint state epoch #${finalized.epoch} root ${rootHex}`);
     }
     if (finalizedStateOrBytes instanceof Uint8Array) {
       const slot = getStateSlotFromBytes(finalizedStateOrBytes);
+      timer = metrics?.processFinalizedCheckpoint.frequencyStateArchive.startTimer();
       await this.db.stateArchive.putBinary(slot, finalizedStateOrBytes);
+      timer?.({step: FrequencyStateArchiveStep.PersistState});
       this.logger.verbose("Archived finalized state bytes", {epoch: finalized.epoch, slot, root: rootHex});
     } else {
       // serialize state using BufferPool if provided
-      const timer = metrics?.stateSerializeDuration.startTimer({source: AllocSource.ARCHIVE_STATE});
+      const sszTimer = metrics?.stateSerializeDuration.startTimer({source: AllocSource.ARCHIVE_STATE});
       await serializeState(
         finalizedStateOrBytes,
         AllocSource.ARCHIVE_STATE,
-        (stateBytes) => {
-          timer?.();
-          return this.db.stateArchive.putBinary(finalizedStateOrBytes.slot, stateBytes);
+        async (stateBytes) => {
+          sszTimer?.();
+          timer = metrics?.processFinalizedCheckpoint.frequencyStateArchive.startTimer();
+          await this.db.stateArchive.putBinary(finalizedStateOrBytes.slot, stateBytes);
+          timer?.({step: FrequencyStateArchiveStep.PersistState});
         },
         this.bufferPool
       );

packages/beacon-node/src/metrics/metrics/lodestar.ts

@@ -1,5 +1,7 @@
 /** biome-ignore-all lint/suspicious/noTemplateCurlyInString: The metric templates requires to have `${}` in a normal string */
 import {NotReorgedReason} from "@lodestar/fork-choice";
+import {ArchiveStoreTask} from "../../chain/archiveStore/archiveStore.js";
+import {FrequencyStateArchiveStep} from "../../chain/archiveStore/strategies/frequencyStateArchiveStrategy.js";
 import {BlockInputSource} from "../../chain/blocks/blockInput/index.js";
 import {JobQueueItemType} from "../../chain/bls/index.js";
 import {AttestationErrorCode, BlockErrorCode} from "../../chain/errors/index.js";
@@ -1420,6 +1422,21 @@ export function createLodestarMetrics(
       },
     },
 
+    processFinalizedCheckpoint: {
+      durationByTask: register.histogram<{source: ArchiveStoreTask}>({
+        name: "lodestar_process_finalized_checkpoint_seconds",
+        help: "Histogram of time to process finalized checkpoint",
+        buckets: [0.1, 0.5, 1, 2, 4, 8],
+        labelNames: ["source"],
+      }),
+      frequencyStateArchive: register.histogram<{step: FrequencyStateArchiveStep}>({
+        name: "lodestar_process_finalized_checkpoint_frequency_state_archive_seconds",
+        help: "Histogram of FrequencyStateArchive duration by step",
+        buckets: [0.1, 0.5, 1, 2, 4, 8],
+        labelNames: ["step"],
+      }),
+    },
+
     regenFnCallTotal: register.gauge<{entrypoint: RegenFnName; caller: RegenCaller}>({
       name: "lodestar_regen_fn_call_total",
       help: "Total number of calls for regen functions",