What's the difference between Thread.setPriority() and android.os.Process.setThreadPriority()

Question

If I have code like:

Runnable r = ...;

Thread  thread = new Thread(r);
thread.setPriority((Thread.MAX_PRIORITY + Thread.NORM_PRIORITY) / 2);

or ...

    Runnable r = ...
    Thread thread = new Thread( new Runnable() {
       public void run() {
         android.os.Process.setThreadPriority(android.os.Process.THREAD_PRIORITY_MORE_FAVORABLE);
         r.run();
       }
    });

IS the android.os.Process way required/preferred?

WHY is the android.os.Process way preferred/required if it is?

This is not clearly documented as far as I can tell.

Answer 1

I would rely on thread.setPriority(). The android.os.Process.setThreadPriority names a real thread priority of the underliying linux OS. However, those could, but doesn't need to map to Dalvik / Java VM threads, as the VM could do threading on its own means or use system threads or a combination of both. Raising the system priority would more likely result in prioritizing your application in favor of others, if not restricted by android security constraints, but not guarantee prioritizing your current Java Thread in favor of other Java Threads in your application.

Answer 2

Google uses

Process.setThreadPriority(Process.THREAD_PRIORITY_BACKGROUND);

in Volley's Network Dispatcher thread, so I would believe that using Process.setThreadPriority() is the way to go.