ExecutorCompletionService missing invokeAll interface

Question

So reading the javadoc of ExecutorCompletionService , looks like it uses threadpoolexecutor that has methods like invokeAll() , however, the ExecutorCompletionService only provides submit() method, therefore not allowing us to call invokeAll and triggering all tasks at once if tasks are submitted through the ExecutorCompletionService .

Should not it support invokeAll() so that I can prepare a list of tasks and call something like

ExecutorCompletionService.invokeAll(listOfTasks);

instead of calling

ExecutorCompletionService.submit(task);

in a for loop?

Answer 1

No. An ExecutorCompletionService is a CompletionService , not an ExecutorService . The whole point of a CompletionService is to provide a mechanism to check for completed tasks through polling.

invokeAll blocks until all submitted tasks are completed.

These are opposing features.