Shuwdown executors after executing all tasks.

    public static void shutdownAllExecutors() {

        synchronized(sExecutorMap) {

            for (final PrioritizedSerialExecutor executor : sExecutorMap.values()) {

                executor.execute(new Runnable() {

                    @Override

                    public void run() {

                        executor.shutdown();

                        sExecutorMap.remove(executor);

                    }

                });

            }

        }

    }

}