Custom ThreadPoolExecutor

CustomThreadPoolExecutor.java

static class CustomThreadPoolExecutor extends ThreadPoolExecutor {
    CustomThreadPoolExecutor(int corePoolSize,
                             int maxPoolSize,
                             long keepAliveTime,
                             TimeUnit unit,
                             BlockingQueue blockingQueue) {
        super(corePoolSize, maxPoolSize, keepAliveTime, unit, blockingQueue,
                SearchThreadFactory.newThreadFactory(),
                new CallerRunsPolicy());
    }

    CustomThreadPoolExecutor() {
        this(Runtime.getRuntime().availableProcessors(),
                Runtime.getRuntime().availableProcessors() * 2,
                1, TimeUnit.SECONDS,
                new ArrayBlockingQueue<Runnable>(20));
        System.out.println("No of available processors: " + Runtime.getRuntime().availableProcessors());
    }

    private final ThreadLocal elapsed_time = new ThreadLocal();

    @Override
    public void beforeExecute(Thread t, Runnable r) {
        elapsed_time.set(System.nanoTime());
    }

    @Override
    public void afterExecute(Runnable r, Throwable t) {
        long startTime = (Long) elapsed_time.get();
        long elapsedTime = System.nanoTime() - startTime;
        logger.info("Completed in {}ms", elapsedTime / Math.pow(10, 6));
    }
}

static class SearchThreadFactory implements ThreadFactory {
    int count;

    @Override
    public Thread newThread(Runnable r) {
        count++;
        return new Thread(r, "SearchThread_" + count);
    }

    public static ThreadFactory newThreadFactory() {
        return new SearchThreadFactory();
    }
}

1. A custom ThreadPoolExecutor is created with twice as many available CPU cores
2. A custom ThreadFactory is created and passed to the ThreadPoolExecutor to give identifiable names to pool threads