CODEWITHSUNDEEP
javaconcurrency
user2030415
user2030415

Reputation:

Usage of ThreadPoolExecutor after extending

According to Java concurrency in practice if we want to add logging, timing, monitoring facility to ThreadPoolExecutor then we should extend it. Suppose if we extend it like below:

// code taken from java concurrency in practice

public class TimingThreadPool extends ThreadPoolExecutor 
{
private final ThreadLocal<Long> startTime
        = new ThreadLocal<Long>();
private final Logger log = Logger.getLogger("TimingThreadPool");
private final AtomicLong numTasks = new AtomicLong();
private final AtomicLong totalTime = new AtomicLong();

protected void beforeExecute(Thread t, Runnable r) {
    super.beforeExecute(t, r);
    log.fine(String.format("Thread %s: start %s", t, r));
    startTime.set(System.nanoTime());
}

protected void afterExecute(Runnable r, Throwable t) {
    try {
        long endTime = System.nanoTime();
        long taskTime = endTime - startTime.get();
        numTasks.incrementAndGet();
        totalTime.addAndGet(taskTime);
        log.fine(String.format("Thread %s: end %s, time=%dns",
                t, r, taskTime));
    } finally {
        super.afterExecute(r, t);
    }
}

protected void terminated() {
    try {
        log.info(String.format("Terminated: avg time=%dns",
                totalTime.get() / numTasks.get()));
    } finally {
        super.terminated();
    }
}
}

Here my doubt is how will you use this class, because if you create ExecutorService it always returns an instance of ThreadPoolExecutor. So how will u plug this class to show the loggings (need client code to use this).

Thanks in advance!!! Sorry if i made any mistake while mentioning the question.

Upvotes: 2

Views: 4482

Answers (1)

Evgeniy Dorofeev
Evgeniy Dorofeev

Reputation: 136112

Your class is missing constuctors, it wont work without them

public class TimingThreadPool extends ThreadPoolExecutor {
    public TimingThreadPool(int corePoolSize, int maximumPoolSize, long keepAliveTime, TimeUnit unit,
            BlockingQueue<Runnable> workQueue) {
        super(corePoolSize, maximumPoolSize, keepAliveTime, unit, workQueue);
    }

    // ...
}

Besides you could take a look at Executors implementation and do something similar in your class 

public static ExecutorService newFixedThreadPool(int nThreads) {
    return new TimingThreadPool(nThreads, nThreads,
            0L, TimeUnit.MILLISECONDS,
            new LinkedBlockingQueue<Runnable>());
}

Upvotes: 4

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