Particular Thread Count

Question

I want to know how many active threads are there for a particular Thread class. Lets say I have a class T which extends thread. In some other class (Ex: Demo) , I want to get t

Answer 1

You can use Thread.enumerate():

public int countThreadsOfClass(Class<? extends Thread> clazz) {
    Thread[] tarray = new Thread[Thread.activeCount()];
    Thread.enumerate(tarray);
    int count = 0;
    for(Thread t : tarray) {
        if(clazz.isInstance(t))
            count++;
    }
    return count;
}

Answer 2

You could implement ThreadFactory to construct the custom Thread classes and supply a ThreadGroup instance to get the counts from. By using ThreadFactory, each instance could contain its own ThreadGroup, making counts accessible based on the factory used.

Answer 3

Try to use ThreadPoolExecutor. You can extend the ThreadPoolExecutor and counts the number of threads by calling getActiveCount().

http://docs.oracle.com/javase/6/docs/api/java/util/concurrent/ThreadPoolExecutor.html

Answer 4

Your Thread (or Runnable) subclass can maintain a static active count. Increment when run() starts, decrement when run() ends (in a finally block).

Make sure the increment/decrement is done in a multithread secure way.

Answer 5

   private static int getThreadCount(){
        int runningThread = 0;
        for (Thread t : Thread.getAllStackTraces().keySet()) if (t.getState()==Thread.State.RUNNABLE && t instanceof YourThreadClassName ) runningThread++;
        System.out.println("Active threads : "+runningThread);
        return runningThread;
    }

Justreplace YourThreadClassName with your class that is extended by Thread.