CallerBlocksPolicy as alternative to CallerRunsPolicy if the calling thread and the pool threads(tasks) share a similar thread local which would then be messed up.

CallerBlocksPolicy.java

    public static ExecutorService createDefaultPool() {
        int threads = Runtime.getRuntime().availableProcessors()*2;
        int queueSize = threads * 25;
        return new ThreadPoolExecutor(threads / 2, threads, 30L, TimeUnit.SECONDS, new ArrayBlockingQueue<>(queueSize),
                new CallerBlocksPolicy());
//                new ThreadPoolExecutor.CallerRunsPolicy());
    }
    static class CallerBlocksPolicy implements RejectedExecutionHandler {
        @Override
        public void rejectedExecution(Runnable r, ThreadPoolExecutor executor) {
            if (!executor.isShutdown()) {
                LockSupport.parkNanos(100);
                try {
                    // submit again
                    executor.submit(r).get();
                } catch (InterruptedException | ExecutionException e) {
                    throw new RuntimeException(e);
                }
            }
        }
    }