Difference between Fixed thread pool and cached thread pool.

Question

Difference between Fixed thread pool and cached thread pool.

JavaServer Side ProgrammingProgramming

---

---

Executor framework are designed using thread pool concept. Thread pool is the way to reuse the already created thread instead of creating a new thread every time to execute the current task.

Executors class provides a factory method to create thread pools. The ThreadPoolExecutor class is the base implementation for the executors that are returned from many of the Executors  factory methods.

Sr. No.	Key	Fixed Thread Pool	Cached Thread Pool
1	Basic	As per Java Doc − Creates a thread pool that reuses a fixed number of threads operating off a shared unbounded queue. At any point, at most nThreads threads will be active processing tasks. If additional tasks are submitted when all threads are active, they will wait in the queue until a thread is available. If any thread terminates due to a failure during execution prior to shutdown, a new one will take its place if needed to execute subsequent tasks. The threads in the pool will exist until it is explicitly shutdown.	As per Java Doc − Creates a thread pool that creates new threads as needed, but will reuse previously constructed threads when they are available. These pools will typically improve the performance of programs that execute many short-lived asynchronous tasks. Calls to execute will reuse previously constructed threads if available. If no existing thread is available, a new thread will be created and added to the pool.
2	Queue	It uses Blocking Queue.	It uses SynchronousQueue queue .
3	Thread Lifetime	It  will keep all the threads running until they are explicitly terminated	Threads that have not been used for sixty seconds are terminated and removed from the cache
4.	Thread Pool Size	The thread pool size is fixed so it won’t grow.	The thread pool can grow from zero threads to Integer.MAX_VALUE
5.	Use Case	We should used fixedthreadpool, when we wanted to limit the concurrent task	It can be used when you have lots of predictable tasks.

Example of Fixed thread pool

public class Main {
   public static void main(String args[]) throws InterruptedException {
      ExecutorService executors = Executors.newFixedThreadPool(4);
      CountDownLatch latch= new CountDownLatch(2);
      executors.submit(new Service1(latch));
      executors.submit(new Service2(latch));
      latch.await();
      System.out.println("Done");
   }

import java.util.concurrent.CountDownLatch;
public class Service1 implements Runnable {
   CountDownLatch latch;
   public Service1(CountDownLatch latch) {
      super();
      this.latch = latch;
   }
   @Override
   public void run() {
      try {
         Thread.sleep(20000);
      } catch (InterruptedException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
         }
         latch.countDown();
         System.out.println("Services2"+latch.getCount());
      }
   }
   import java.util.concurrent.CountDownLatch;
   public class Service2 implements Runnable {
      CountDownLatch latch;
      public Service2(CountDownLatch latch) {
         super();
         this.latch = latch;
      }
      @Override
      public void run() {
         try {
            Thread.sleep(20000);
         } catch (InterruptedException e) {
         // TODO Auto-generated catch block
         e.printStackTrace();
      }
   latch.countDown();
   System.out.println("Services2"+latch.getCount());
   }
}

Himanshu shriv

Published on 09-Sep-2020 13:10:23

Previous Page Print Page

Next Page  

Advertisements