Example of ThreadPoolExecutor.CallerRunsPolicy in Java

By Arvind Rai, January 09, 2013

1. ThreadPoolExecutor.CallerRunsPolicy belongs to java.util.concurrent package. It has been introduced in JDK 1.5.
2. ThreadPoolExecutor.CallerRunsPolicy is the handler for rejected task. ThreadPoolExecutor.CallerRunsPolicy executes the rejected task itself.
3. ThreadPoolExecutor.CallerRunsPolicy has a method rejectedExecution(Runnable r, ThreadPoolExecutor e) which accepts a thread and ThreadPoolExecutor.

ThreadPoolExecutor.CallerRunsPolicy is passed as an argument while initializing ThreadPoolExecutor.

ThreadPoolExecutor  tpool= new ThreadPoolExecutor(2,3,500, TimeUnit.MILLISECONDS,
	new LinkedBlockingQueue<Runnable>(), new ThreadPoolExecutor.CallerRunsPolicy());

Find the sample example.

CallerRunsPolicyDemo.java

package com.concretepage;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;
public class CallerRunsPolicyDemo {
	   class DemoThread implements Runnable {
		   public void run() {
		    	 System.out.println("Hello World");
	           }
	   }
	   public static void main(String... args) {
		   Runnable th=new CallerRunsPolicyDemo().new DemoThread();
		     
		   ThreadPoolExecutor  tpool= new ThreadPoolExecutor(2,3,500, TimeUnit.MILLISECONDS,
		    		 new LinkedBlockingQueue<Runnable>(), new ThreadPoolExecutor.CallerRunsPolicy());
		     
		   tpool.execute(th);
	   }
}

Output