Question

I have an unusual problem.
I have a function, operation in this function can be done by two threads at a time.

static int iCount = 1;
public synchronized void myFunct(){ 
while(iCount >= 3)
{
   try {
       wait();
   } catch (InterruptedException e) {
       e.printStackTrace();
 }

 iCount++; 

 //Do Stuffs
 //After operation decrement count

 iCount --;
 notifyAll();
}

What i am trying to do is, i want to allow only two threads to do some operation, and other threads must wait.

But here first two threads increment the count and does the operation and other threads go for an wait state but do not get the notification.

I guess i am overlooking something.

Answer 1

Sounds like you want to use a Semaphore, you always call acquire() before doing your operation, and then release() in a finally block.

private static final Semphore semaphore = new Semaphore(2);

public static void myFunct() throws InterruptedException {
    semaphore.aquire();
    try {
        // do stuff
    } finally {
        semaphore.release();
    }
}