Thread Priorities

Thread Priorities

Threads always run with some priority, that helps operating system to decide the order in which the threads are scheduled.

Java thread priorities lies between MIN_PRIORITY as a number 1 and MAX_PRIORITY as a number 10 and by default every thread has a priority of 5.

The scheduler uses preemptive, priority based scheduling mainly or time slicing scheduling to schedule the tasks

Preemptive, priority based Scheduling :- If a high priority thread enters into the runnable state than the high priority thread task executes until it  enters to wait/dead state or it will be bumped back to runnable if a higher priority task will came into existence.

Time Slicing Scheduling: - In this cases each thread is allocated a predefined slice of time and then it will sent back to runnable to give another thread a chance

Please note : Even if all threads are of equal priorities ,behavior is not guaranteed ,it means

1)      Scheduler can pick a thread to execute and run it until it enters to wait or dead state

2)      It can do time slicing to provide equal opportunities.

How to set a thread priority ?

Thread_object.setPriority(<int_value>);

Example:

/*

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 * To change this template file, choose Tools | Templates

 * and open the template in the editor.

 */

package multithreadingtc;

/**

 *

 * @author shashank

 */

class Multithreading implements Runnable

{

     public void run()

    {

        for(int i=1;i<=10;i++)

        {

            System.out.println("run by" + Thread.currentThread().getName() + " remainder is i is " +i%10);

//            try

//            {

//                Thread.sleep(1000);

//            }catch(InterruptedException ex){}

        }

    }

}

public class MultithreadingTC{

    public static void main(String[] args) {

        // TODO code application logic here

        Multithreading th = new Multithreading();

        Thread t = new Thread(th);

        t.setName(" first");

        t.setPriority(8);

        t.start();

        Thread t2 = new Thread(th);

        t2.setPriority(6);

        t2.setName(" third");

        t2.start();

        Thread t1 = new Thread(th);

        t1.setName(" second");

        t1.setPriority(4);

        t1.start();

      

    }

   

}