Question

In my java application I have many threads, but there are several most important threads, which do complex calculations (accessing remote db’s, etc).

In case all these important threads are died, then I need to quit the application, even less important threads still are running.

I implemented an additional (thread) class to monitor these threads with core functionality like this:

   boolean allThreadsDied;
   do {
      allThreadsDied = true;
      for (Thread oneThread : threadsList) {
         allThreadsDied = allThreadsDied & (!oneThread.isAlive());
      }
   } while (!allThreadsDied);

   // now, it's time to quit the application

This thread runs permanently and checks the state of important threads.

I think I have invented a bicycle, and very non-efficient bicycle. Because this thread, running permanently, produces high processor load, even when there are no current calculations.

My question is as follows: is there a more efficient way to monitor a group of threads and get a signal when all these threads are died ?

Answer 1

Mark all non-important threads as daemon threads (see: Thread.setDaemon()) and start all important ones normally.

Once all non-daemon threads are dead/done, the JVM quits automatically.