Tracking thread pool in Java
This article presents an implementation of a tracking thread pool in Java.
A tracking thread pool is a usual thread pool that records the task execution statistics like total number of tasks executed, average execution time of tasks and total execution time of all tasks. The default thread pools created by Executors class in Java does not track the execution stats leaving you no option but to implement your own thread pool that does the job.
In this article, I present an implementation of a tracking thread pool that tracks the total execution time, average execution time and the total tasks executed and provides methods to query those parameters. This is quite a powerful feature to have in a thread pool.
You can go a step further and expose these thread statistics through a JMX bean that can be queried and monitored through monitoring tools whenever desired.
Here is the implementation.
TrackingThreadPool.java
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/* * TrackingThreadPool - A thread pool that tracks task execution statistics * * Copyright (c) 2015-2016, Wilddiary.com * All rights reserved. * * Redistribution and use in source and binary forms, with or without modification, are permitted provided that the * following conditions are met: * * 1. Redistributions of source code must retain the above copyright notice, this list of conditions and the * following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the * following disclaimer in the documentation and/or other materials provided with the distribution. * 3. The name of the author may not be used to endorse or promote products derived from this software without * specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL * THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE * POSSIBILITY OF SUCH DAMAGE. */ package com.wilddiary.concurrency; import java.util.Collections; import java.util.Map; import java.util.Set; import java.util.concurrent.BlockingQueue; import java.util.concurrent.ConcurrentHashMap; import java.util.concurrent.ThreadFactory; import java.util.concurrent.ThreadPoolExecutor; import java.util.concurrent.TimeUnit; public class TrackingThreadPool extends ThreadPoolExecutor { // holds in-progress tasks private final Map<Runnable, Boolean> inProgress = new ConcurrentHashMap<Runnable,Boolean>(); // holds startime of the currently executing task. // Each thread has its own copy of this variable private final ThreadLocal<Long> startTime = new ThreadLocal<Long>(); private volatile long totalTime; // in ms private volatile long totalTasks; // Constructor public TrackingThreadPool(int corePoolSize, int maximumPoolSize, long keepAliveTime, TimeUnit unit, BlockingQueue<Runnable> workQueue, ThreadFactory factory) { super(corePoolSize, maximumPoolSize, keepAliveTime, unit, workQueue, factory); } // Called by each thread before executing a task // The executing thread is t and the executed task is r protected void beforeExecute(Thread t, Runnable r) { super.beforeExecute(t, r); inProgress.put(r, Boolean.TRUE); // record the start time startTime.set(new Long(System.currentTimeMillis())); } // Called by each thread after executing the task // The executing thread is t and the executed task is r protected void afterExecute(Runnable r, Throwable t) { // calculate the time taken by the task to execute long time = System.currentTimeMillis() - startTime.get().longValue(); synchronized (this) { // update the stats of the pool totalTime += time; ++totalTasks; } inProgress.remove(r); super.afterExecute(r, t); } /** * @return - returns the currently executing tasks */ public Set<Runnable> getInProgressTasks() { return Collections.unmodifiableSet(inProgress.keySet()); } /** * @return - returns the total tasks executed till that moment */ public synchronized long getTotalTasks() { return totalTasks; } /** * @return - returns the average execution time of tasks in ms */ public synchronized double getAverageExecutionTime() { return (totalTasks == 0) ? 0 : totalTime / (double) totalTasks; } /** * @return - returns the total execution time of tasks in ms */ public synchronized long getTotalExecutionTime() { return totalTime; } } |
TrackingThreadPool tester
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package com.wilddiary.concurrency; import java.util.Random; import java.util.concurrent.LinkedBlockingQueue; import java.util.concurrent.ThreadFactory; import java.util.concurrent.TimeUnit; /** * Tracking thread pool tester * * @author Drona */ public class TrackingThreadPoolTest { public static void main(String[] args) throws InterruptedException { // create the tracking thread pool with 5 threads final TrackingThreadPool pool = newTrackingThreadPool(5); // submit some tasks for execution for (int i = 0; i < 50; i++) { pool.submit(new RandomNumberPrinterTask()); } // shutdown the pool pool.shutdown(); // await shutdown while (!pool.isTerminated()){ pool.awaitTermination(2, TimeUnit.SECONDS); } // print the execution stats System.out.println("----------------------------------"); System.out.println("Total tasks executed = " + pool.getTotalTasks()); System.out.println("Average execution time = " + pool.getAverageExecutionTime() + " ms"); System.out.println("Total execution time = " + pool.getTotalExecutionTime() + " ms"); System.out.println("----------------------------------"); } /** * Factory method to create the tracking thread pool with the given number * of threads * * @param numOfThreads * @return */ private static TrackingThreadPool newTrackingThreadPool(int numOfThreads){ return new TrackingThreadPool(numOfThreads, numOfThreads, 0L, TimeUnit.MILLISECONDS, new LinkedBlockingQueue<Runnable>(), new ThreadFactory() { @Override public Thread newThread(Runnable r) { Thread t = new Thread(r); t.setUncaughtExceptionHandler(new Thread.UncaughtExceptionHandler() { @Override public void uncaughtException(Thread t, Throwable e) { System.err.println("Thread terminated due to exception - " + e.getMessage()); } }); return t; } }); } /** * Random number printer task. * * @author Drona * */ static class RandomNumberPrinterTask implements Runnable{ @Override public void run() { int random = new Random().nextInt(100); System.out.println(Thread.currentThread().getName() + " - " + random); try { Thread.sleep(random); } catch (InterruptedException e) { System.err.println("Thread interrupted"); } } } } |
Output
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Thread-2 - 90 Thread-3 - 87 Thread-1 - 54 Thread-4 - 43 Thread-0 - 49 Thread-4 - 87 Thread-0 - 72 Thread-1 - 10 Thread-1 - 53 Thread-3 - 44 Thread-2 - 98 Thread-1 - 12 Thread-0 - 97 Thread-1 - 77 Thread-4 - 44 Thread-3 - 53 Thread-4 - 0 Thread-4 - 38 Thread-2 - 70 Thread-3 - 53 Thread-1 - 66 Thread-0 - 38 Thread-4 - 72 Thread-3 - 78 Thread-2 - 72 Thread-0 - 15 Thread-0 - 11 Thread-1 - 8 Thread-0 - 68 Thread-1 - 43 Thread-4 - 24 Thread-4 - 78 Thread-3 - 5 Thread-3 - 36 Thread-2 - 85 Thread-1 - 67 Thread-0 - 51 Thread-3 - 19 Thread-3 - 40 Thread-4 - 16 Thread-1 - 34 Thread-0 - 56 Thread-4 - 52 Thread-2 - 90 Thread-3 - 15 Thread-1 - 46 Thread-3 - 60 Thread-0 - 97 Thread-4 - 19 Thread-1 - 95 ---------------------------------- Total tasks executed = 50 Average execution time = 54.72 ms Total execution time = 2736 ms ---------------------------------- |
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