schedule() is not running exactly after expiry of each entry, it works only for first entry expiry

[nemadev888]

Hi Team,

I am using below code snippet to create cache manager:

CaffeineCache cache = new CaffeinceCache("poc-cache", Caffeince.newBuilder()
.scheduler(Scheduler.forScheduledExecutorService(new ScheduledTheadpoolExecutor(1)))
.expiryAfterWrite(60, TimeUnit.SECONDS)
.removalListener(new CustomRemovalListener())
.maximumSize(10)
.build())

In my case, I want to achieve below things:

1. After exactly expiring time of each entry, want to invoke removalListener
2. In removal Listener, want to reload the value asynchronously in cache for expired key again

Using version: 2.8.0 and Java 8

output of my code:
2024-04-01 **12:55:12.**760 INFO 33588 --- [nio-8080-exec-2] : cache populated with key: 121
2024-04-01 12:55:45.690 INFO 33588 --- [nio-8080-exec-4] : cache populated with key: 122
2024-04-01 12:56:12.778 INFO 33588 --- [onPool-worker-2] : Expiring the key: 121
2024-04-01 12:56:15.561 INFO 33588 --- [nio-8080-exec-8] : cache populated with key: 123
2024-04-01 12:57:39.862 INFO 33588 --- [onPool-worker-4]: Expiring the key: 123
2024-04-01 12:57:39.862 INFO 33588 --- [nPool-worker-13] : Expiring the key: 122

If you see, for first entry, that removal Listener executed by the scheduler at exact expiry time, but for other 2 entries, it didn't.

Please suggest, if I am missing some thing on cache config.

Regards,
Devesh

[ben-manes]

Perhaps the ForkJoinPool.commonPool() is flooded so the listener is waiting longer than expected. A lot of times it’s overused for blocking IO even though it’s designed for cpu-bound tasks, often because it’s the default executor for CompletableFuture. You can try setting Caffeine.executor(es) to see if that helps.

[nemadev888]

Hi Ben,

ExecutorService es = Executors.newFixedThreadPool(10);
Even after using giving Executor in execuor() function, There is no change in the behavior. does removal Listener not run at the exact time of expiry?
I was reading this page: https://stackoverflow.com/questions/68101454/caffeine-combining-both-scheduler-and-executor-service

Where you mentioned that If the next expiration event is in the distant future then the scheduler won't run until then, though calling threads may trigger a maintenance cycle due to their activity on the cache (see #1,2).

[ben-manes]

I think you’d need to debug it further or reproduce in a test. For example decorate the scheduled executor to print a message when a task is being run to see if it’s prompt. Then see if something is blocking progress if otherwise correct. It should try to run with a 1s tolerance unless something else is obstructing the maintenance process. It’s also possible that an upgrade might help since you are on a pretty old version.

[ben-manes]

Closing due to lack of feedback. If you can provide a sample to that demonstrates this problem, please reopen! I just don't have enough to information to go on.