Randomly seeing "org.springframework.core.task.TaskRejectedException" when employing concurrency attribute of RqueueListener

[sravindran2020]

I randomly see the following exception when specifying the concurrency attribute of @RqueueListener. In this case, I am using a value of 7 for the concurrency property.

Below is the full stack trace. It seems to occur at random, and I am not sure why this occurs or what this implies?

org.springframework.core.task.TaskRejectedException: Executor [java.util.concurrent.ThreadPoolExecutor@1ee46fa1[Running, pool size = 7, active threads = 7, queued tasks = 0, completed tasks = 15]] did not accept task: com.github.sonus21.rqueue.listener.RqueueExecutor@79aa2eac
	at org.springframework.scheduling.concurrent.ThreadPoolTaskExecutor.execute(ThreadPoolTaskExecutor.java:339) ~[spring-context-5.3.15.jar:5.3.15]
	at com.github.sonus21.rqueue.utils.QueueThreadPool.execute(QueueThreadPool.java:57) ~[rqueue-core-2.9.0-RELEASE.jar:na]
	at com.github.sonus21.rqueue.listener.RqueueMessagePoller.execute(RqueueMessagePoller.java:74) ~[rqueue-core-2.9.0-RELEASE.jar:na]
	at com.github.sonus21.rqueue.listener.RqueueMessagePoller.sendMessagesToExecutor(RqueueMessagePoller.java:114) ~[rqueue-core-2.9.0-RELEASE.jar:na]
	at com.github.sonus21.rqueue.listener.RqueueMessagePoller.pollAndExecute(RqueueMessagePoller.java:134) ~[rqueue-core-2.9.0-RELEASE.jar:na]
	at com.github.sonus21.rqueue.listener.RqueueMessagePoller.poll(RqueueMessagePoller.java:159) ~[rqueue-core-2.9.0-RELEASE.jar:na]
	at com.github.sonus21.rqueue.listener.DefaultRqueuePoller.start(DefaultRqueuePoller.java:78) ~[rqueue-core-2.9.0-RELEASE.jar:na]
	at com.github.sonus21.rqueue.utils.RetryableRunnable.run(RetryableRunnable.java:48) ~[rqueue-core-2.9.0-RELEASE.jar:na]
	at java.base/java.util.concurrent.Executors$RunnableAdapter.call(Unknown Source) ~[na:na]
	at java.base/java.util.concurrent.FutureTask.run(Unknown Source) ~[na:na]
	at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source) ~[na:na]
	at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source) ~[na:na]
	at java.base/java.lang.Thread.run(Unknown Source) ~[na:na]
Caused by: java.util.concurrent.RejectedExecutionException: Task com.github.sonus21.rqueue.listener.RqueueExecutor@79aa2eac rejected from java.util.concurrent.ThreadPoolExecutor@1ee46fa1[Running, pool size = 7, active threads = 7, queued tasks = 0, completed tasks = 15]
	at java.base/java.util.concurrent.ThreadPoolExecutor$AbortPolicy.rejectedExecution(Unknown Source) ~[na:na]
	at java.base/java.util.concurrent.ThreadPoolExecutor.reject(Unknown Source) ~[na:na]
	at java.base/java.util.concurrent.ThreadPoolExecutor.execute(Unknown Source) ~[na:na]
	at org.springframework.scheduling.concurrent.ThreadPoolTaskExecutor.execute(ThreadPoolTaskExecutor.java:336) ~[spring-context-5.3.15.jar:5.3.15]
	... 12 common frames omitted

[sonus21]

did you provide your own task executor?

[sravindran2020]

By task executor, do you mean an @RqueueListener for the messages in the queue? If so, yes.

@RqueueListener(value = "QUEUE", concurrency = "7")
public void method()

[sonus21]

No, I meant you set task executor in SimpleRqueueListenerContainerFactory object?

[sravindran2020]

No, the only attribute we set in the queue listener container factory is the exponential back off with unlimited retries.

@Bean
    public SimpleRqueueListenerContainerFactory simpleRqueueListenerContainerFactory() {
        SimpleRqueueListenerContainerFactory factory = new SimpleRqueueListenerContainerFactory();

        // exponential backoff with unlimited retries
        factory.setTaskExecutionBackOff(new ExponentialTaskExecutionBackOff());

        return factory;
    }

[sonus21]

I do understand i can confirm from your other discussion you're using some old version of Rqueue. Please upgrade to newer version 2.10.1 .