How to check if a thread is sleeping?

Question

Is there any way to check if a given thread is sleeping?

Answer 1

i didn't actually did it , but there's an ThreadMXBean Interface for getting thread Info

which returns ThreadInfo Class, there you might get something with getWaitedTime method.

Answer 2

Here is an fairly ugly hack to check if the other thread is sleeping:

public static boolean isSleeping(Thread t) {
    StackTraceElement[] ste = t.getStackTrace();

    if (ste.length == 0)
        return false;     // thread has terminated!

    return ste[0].getClassName().equals("java.lang.Thread")
        && ste[0].getMethodName().equals("sleep");
}

Answer 3

You could create your own sleep method which records the Thread's ID to a global variable and use it as reference for sleeping thread.

There's no other way you can tell if a thread is precisely sleeping.

Hope the three links below help:

• States
• Java Doc 1
• Java Doc 2

Answer 4

You can call Thread.getState() on and check if the state is TIMED_WAITING.

Note, however that TIMED_WAITING doesn't necessarily mean that the thread called sleep(), it could also be waiting in a Object.wait(long) call or something similar.

Answer 5

I am not sure if there is a better way but you could change a variable when a thread goes to sleep and check that variable if the thread is sleeping or not.