MultiThreading in java working in MultiProcessor

[Yugandhar Reddy]

I have an application written in java
I am creating a pool of threads and executing a process on each thread.
If i create a single thread on single processor system and give the process on it, it is taking 30 sec.
if i create two threads on dual processor system and giving the process on each thread, it is taking 54 sec.
I want to know how the dual processor system works in case of multi threading.
Thanks for the help.

[Dan Cranmer]

It might have to do with the platform and JVM you are using. I ran the following code on a 3 processor Sun, when only one thread is created I can only use 33.3% of the CPU, when 2 threads are created it starts to use 66.6% and when all 3 threads are started I use all available processors.

class a extends Thread {
   public void run() {
      while (true){}
   }
   public static void main(String args[]) {
      a a1 = new a();
      a a2 = new a();
      a a3 = new a();
      a1.start();
      a2.start();
      a3.start();
   }
}

[Mr. C Lamont Gilbert]

Can your process be easily divided? some processes do not lend themselves to speed-ups due to multithreading.