From fa30bcf10086292883ef086202474ac4df67ffe1 Mon Sep 17 00:00:00 2001
From: tuyennhv <tuyen@chainsafe.io>
Date: Fri, 10 Nov 2023 19:35:00 +0300
Subject: [PATCH] fix: only transfer cache at epoch transition (#6102)

---
 packages/beacon-node/src/chain/blocks/verifyBlock.ts | 1 +
 packages/beacon-node/src/chain/prepareNextSlot.ts    | 5 +++--
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/packages/beacon-node/src/chain/blocks/verifyBlock.ts b/packages/beacon-node/src/chain/blocks/verifyBlock.ts
index 77c6b4832bbc..4f8bcfa86d01 100644
--- a/packages/beacon-node/src/chain/blocks/verifyBlock.ts
+++ b/packages/beacon-node/src/chain/blocks/verifyBlock.ts
@@ -71,6 +71,7 @@ export async function verifyBlocksInEpoch(
 
   if (!isStateValidatorsNodesPopulated(preState0)) {
     this.logger.verbose("verifyBlocksInEpoch preState0 SSZ cache stats", {
+      slot: preState0.slot,
       cache: isStateValidatorsNodesPopulated(preState0),
       clonedCount: preState0.clonedCount,
       clonedCountWithTransferCache: preState0.clonedCountWithTransferCache,
diff --git a/packages/beacon-node/src/chain/prepareNextSlot.ts b/packages/beacon-node/src/chain/prepareNextSlot.ts
index a1b5c23144d1..43fac1d1b120 100644
--- a/packages/beacon-node/src/chain/prepareNextSlot.ts
+++ b/packages/beacon-node/src/chain/prepareNextSlot.ts
@@ -98,8 +98,9 @@ export class PrepareNextSlotScheduler {
       const prepareState = await this.chain.regen.getBlockSlotState(
         headRoot,
         prepareSlot,
-        // the 1st slot of next epoch will likely use this Previous Root Checkpoint state so we transfer cache here
-        {dontTransferCache: false},
+        // the slot 0 of next epoch will likely use this Previous Root Checkpoint state for state transition so we transfer cache here
+        // for other slots dontTransferCached=true because we don't run state transition on this state
+        {dontTransferCache: !isEpochTransition},
         RegenCaller.precomputeEpoch
       );