Java ServiceExecutor terminating condition

Question

I'm new to java executor stuff.

I'm using Java's ExecutorService to launch several threads to process data.

Executor executor = Executors.newFixedThreadPool(poolSize);

for(int i=0; i< 5;i++) executor.execute(new MyRunnable(i));

once the threads don't find data, they gracefully terminate.

My question is what happens to the Executor when all the threads terminate, is it still running its master thread ? or it will terminate itself and whole application will finish gracefully?

in case executor thread still runs, how can I let it terminate once all its child threads are done (poolSize number of threads).

Answer 1

Executor will keep running with the underlying thread pool. You can still execute or submit a new task. It is recommended to shutdown Executor service call ExecutorService.html#shutdown() which attempts to stop all actively executing tasks, halts the processing of waiting tasks, and returns a list of the tasks that were awaiting execution.

You can also use ExecutorService.html#shutdownNow() which stops all actively executing tasks, halts the processing of waiting tasks, and returns a list of the tasks that were awaiting execution. It is useful when you need immediate shutdown.

Answer 2

1) threads in a fixed thread pool executor never terminate once started

2) there is no master thread in thread pool executor