Returns true if the process of termination has commenced but not yet completed. This method may be useful for debugging. A return of true reported a sufficient period after shutdown may indicate that submitted tasks have ignored or suppressed interruption, or are waiting for I/O, causing this executor not to properly terminate. (See the advisory notes for class Java.Util.Concurrent.ForkJoinTask stating that tasks should not normally entail blocking operations. But if they do, they must abort them on interrupt.)

[Android Documentation]