ExecutorService, how to wait for all tasks to finish?

The simplest approach is to use ExecutorService.invokeAll() which does what you want in a one-liner. In your parlance, you'll need to modify or wrap ComputeDTask to implement Callable which can give you quite a bit more flexibility. Probably in your app there is a meaningful implementation of Callable.call() but here's a way to wrap it if not using Executors.callable() .

If you want to wait for all tasks to complete, use the shutdown method instead of wait. Then follow it with awaitTermination.

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