SimpleAsyncTaskExecutor not releasing threads

Question

I am running several spring batch partitioning jobs from within the same JVM instance. Each is configured to use 3 threads but every time a new job starts I see in the logs that SimpleAsyncTaskExecutor keeps increasing its thread number.

so first jobs shows:

09:53:02.370 [SimpleAsyncTaskExecutor-1] INFO...
09:53:02.370 [SimpleAsyncTaskExecutor-2] INFO...

and next jobs shows:

09:53:02.370 [SimpleAsyncTaskExecutor-3] INFO...
09:53:02.370 [SimpleAsyncTaskExecutor-4] INFO...

I would have expected each new job to use threads 1 and 2 and not create new ones...I am shutting down the job each time but can post code if needed.

Answer 1

SimpleAsyncTaskExecutor does not reuse threads. Furthermore SimpleAsyncTaskExecutor by default creates unlimited threads.

For reuse threads you need to use ThreadPoolTaskExecutor.

Read below for more information:

https://egkatzioura.com/2017/10/25/spring-and-threads-taskexecutor/

https://egkatzioura.com/2017/10/25/spring-and-async/

https://egkatzioura.com/2017/10/25/spring-and-threads-transactions/

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