How all the processors usage become 100% in multithreading

Question

My System is 7 core CPU machine. I just tried running the below program

 for(int i=0;i<10; i++)
 {
        new Thread(new Runnable()
        {   
            @Override
            public void run()
            {
                while (true)
                {

                }   
            }
        }).start();;
    }

Now my full CPU usage is 100%(7 cores are 100%). Here 10 threads are in single Process javaw.exe. How it got split across all of my CPU cores?

Whether a single process can run in multiple cores or whether java implementation take care of giving threads across different processors?

7 core CPU? Never heard of that. – B.K. Dec 05 '14 at 06:12 — B.K., Dec 05 '14 at 06:12
Side note. Intel i7 processor doesn't have 7 cores – arunmoezhi Dec 05 '14 at 09:43 — arunmoezhi, Dec 05 '14 at 09:43
@arunmoezhi oh. new info for me.. Thanks. – Sangeeth Dec 05 '14 at 10:12 — Sangeeth, Dec 05 '14 at 10:12

score 1 · Accepted Answer · edited May 23 '17 at 10:33

Yes, multiple threads of the same process can be split across multiple CPU. For many applications, that is the whole point of using multiple threads.

Most current JVM implementations use native OS threads for this (one Java thread - one OS thread), so this is all done by the operating system. The alternative would be "green threads" where the JVM would manually schedule execution. This seems to be a thing of the past, for architectures or OS without "real" threads.

How all the processors usage become 100% in multithreading

1 Answers1