hollow/src/main/java/com/netflix/hollow/core/util/SimultaneousExecutor.java
public void awaitSuccessfulCompletionOfCurrentTasks() throws InterruptedException, ExecutionException {
        for(Future<?> f : futures) {
            f.get();
        }

        futures.clear();
    }
public void awaitSuccessfulCompletionOfCurrentTasks() throws InterruptedException, ExecutionException {
        for(Future<?> f : futures) {
            f.get();
        }

        futures.clear();
    }
Await successful completion of all previously submitted tasks.  Throw exception of the first failed task
if 1 or more tasks failed.

After this call completes, the thread pool will <i>not</i> be shut down and can be reused.

@throws ExecutionException if a computation threw an
exception
@throws InterruptedException if the current thread was interrupted
while waiting