disable prefetch on every other attempt only, to make sure we are not…

… permanently breaking anything

src/DurableTask.Netherite/StorageLayer/Faster/PartitionStorage.cs

@@ -191,9 +191,11 @@ async Task TerminationWrapper(Task what)
                     {
                         // replay log as the store checkpoint lags behind the log
 
-                        // disable prefetch if we have had many unsuccessful recovery attempts, or if the settings say so    
-                        // We choose 6 as the threshold since the tracing gets boosted after 3 attempts, and we want to see 3 attempts with boosted tracing before we disable prefetch
-                        bool disablePrefetch = this.blobManager.CheckpointInfo.RecoveryAttempts > 6 || this.settings.DisablePrefetchDuringReplay;
+                        // after six unsuccessful attempts, we start disabling prefetch on every other attempt, to see if this can remedy the problem
+                        int startDisablingPrefetchAfter = 6;
+
+                        bool disablePrefetch = this.settings.DisablePrefetchDuringReplay
+                            || (this.blobManager.CheckpointInfo.RecoveryAttempts > startDisablingPrefetchAfter && (this.blobManager.CheckpointInfo.RecoveryAttempts - startDisablingPrefetchAfter) % 2 == 1);
 
                         await this.TerminationWrapper(this.storeWorker.ReplayCommitLog(this.logWorker, prefetch: !disablePrefetch));
                     }