feat: debug too many shuffling promises

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

@@ -114,7 +114,7 @@ export class PrepareNextSlotScheduler {
         // the slot 0 of next epoch will likely use this Previous Root Checkpoint state for state transition so we transfer cache here
         // the resulting state with cache will be cached in Checkpoint State Cache which is used for the upcoming block processing
         // for other slots dontTransferCached=true because we don't run state transition on this state
-        {dontTransferCache: !isEpochTransition},
+        {dontTransferCache: !isEpochTransition, asyncShufflingCalculation: true},
         RegenCaller.precomputeEpoch
       );
 

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

@@ -30,6 +30,10 @@ export enum RegenFnName {
 
 export type StateCloneOpts = {
   dontTransferCache: boolean;
+  /**
+   * Do not queue shuffling calculation async. Forces sync JIT calculation in afterProcessEpoch
+   */
+  asyncShufflingCalculation?: boolean;
 };
 
 export interface IStateRegenerator extends IStateRegeneratorInternal {

packages/state-transition/src/cache/epochCache.ts

@@ -667,10 +667,13 @@ export class EpochCache {
       this.shufflingCache
         .get(epochAfterUpcoming, this.nextDecisionRoot)
         .then((shuffling) => {
-          if (!shuffling) {
-            throw new Error("EpochShuffling not returned from get in afterProcessEpoch");
-          }
-          this.nextShuffling = shuffling;
+          this.nextShuffling = shuffling
+            ? shuffling
+            : // biome-ignore lint/style/noNonNullAssertion: object must be defined to be in this branch of the conditional
+              this.shufflingCache!.getSync(epochAfterUpcoming, this.nextDecisionRoot, {
+                state,
+                activeIndices: this.nextActiveIndices,
+              });
         })
         .catch((err) => {
           this.shufflingCache?.logger?.error(

packages/state-transition/src/cache/epochTransitionCache.ts

@@ -28,6 +28,10 @@ export type EpochTransitionCacheOpts = {
    * Assert progressive balances the same to EpochTransitionCache
    */
   assertCorrectProgressiveBalances?: boolean;
+  /**
+   * Do not queue shuffling calculation async. Forces sync JIT calculation in afterProcessEpoch
+   */
+  asyncShufflingCalculation?: boolean;
 };
 
 /**
@@ -376,7 +380,10 @@ export function beforeProcessEpoch(
   for (let i = 0; i < nextEpochShufflingActiveIndicesLength; i++) {
     nextShufflingActiveIndices[i] = nextEpochShufflingActiveValidatorIndices[i];
   }
-  state.epochCtx.shufflingCache?.build(epochAfterNext, nextShufflingDecisionRoot, state, nextShufflingActiveIndices);
+
+  if (opts?.asyncShufflingCalculation) {
+    state.epochCtx.shufflingCache?.build(epochAfterNext, nextShufflingDecisionRoot, state, nextShufflingActiveIndices);
+  }
 
   if (totalActiveStakeByIncrement < 1) {
     totalActiveStakeByIncrement = 1;