private void resumeAfterDrain() {
    log.trace("Resume loop thread");
    if (coordinatorRequests.shouldShutdownNow()) {
      shutdownNow = true;
    }
    synchronized (latch) {
      latch.notifyAll();
      runLoopResumedSinceLastChecked = true;
    }
  }
Resume the runloop thread. This method is triggered after a task has completed drain.
samza-core/src/main/java/org/apache/samza/container/RunLoop.java