Java | Terminating all child threads if parent thread is terminated

Question

Please help me with this Main thread/ Parent thread will triggers sub threads. If we are stopping parent/main thread it must also stop all child/sub threads

I am thinking to do it with interrupts but not able to do it Please help me out with the code

and how to ensure all child threads have been stopped?IS there any way to do this also

Thanks in Advance!

I am trying to do something like this :

public class ThreadTest1 extends Thread{ private static final Logger LOGGER = Logger.getLogger("mylogger");

public void run(){  


      for(int i=1;i<=5;i++){  
       try{  
           if (!Thread.currentThread().isInterrupted()) {
               LOGGER.log(Level.SEVERE,"Sleeping...");
               Thread.sleep(1000);
               LOGGER.log(Level.SEVERE,"Processing");
               System.out.println(Thread.currentThread().getId()+"Thread id:    "+i);  
           }
           else{
               throw new InterruptedException();
           }




       }catch(InterruptedException e){
           System.out.println(e);
           LOGGER.log(Level.SEVERE,"Exception", e);
           Thread.currentThread().interrupt();

       }  

      }  
     }  
    public static void main(String args[]){  

        ThreadTest1 t1=new ThreadTest1();  
        ThreadTest1 t2=new ThreadTest1();  
        ThreadTest1 t3=new ThreadTest1();  
        System.out.println(t1.getId());
        System.out.println(t2.getId());
        System.out.println(t3.getId());

        t1.start();  
        t2.start();  
        t3.start();
        System.out.println("Do you want to kill all processes: Press any key to continue");
        int s=0;
        try {
            s = System.in.read();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
            if(s!=0){

            t1.interrupt();
            t2.interrupt();
            t3.interrupt();
        }

            System.out.println(t1.isAlive());

     }

}

Please help me out with the code Which code? You should put your code here to let others know what you are trying to do. — gprathour
Maybe ThreadGroup will help? If you put all child threads in the same ThreadGroup, you can interrupt them all. The child threads still have to cooperate by checking periodically. — ajb
thanks @ajb I will try to do it with Theadgroups. Even I am also not sure of it will work with Threadgroup or not — bhanuj
OK, thanks for posting the code... What are the symptoms? The code looks like it should kill the threads, but you didn't wait long enough before checking t1.isAlive. The interrupt will take a little time to process. Also, are you sure it recognized the input? On many systems, if you simply "press a key", the input will not get to the program until you press ENTER or RETURN. — ajb

Niels Niels · Accepted Answer · 2014-12-09T08:11:40

Java automatically groups Threads. If you do not define a specific ThreadGroup, it will always grouped as child of the thread where the initialization takes place.

So if you abort a parent Thread, all its childThreads will be aborted too.

perhaps this could help (sorry that it's in german): dpunkt programming pdf

Java | Terminating all child threads if parent thread is terminated

1 Answers