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);

Answer 1

The current Dalvik implementation seems to map Java Threads one by one to the underlying linux system PTHREADs like you say. All Threads of all apps belong to the same thread group on the system, so every Thread competes with all Threads of all apps.

So currently Thread.setPriority should actually do the same thing as Process.setThreadPriority, using the smaller Java priority scale. The mapping of priorities is defined in kNiceValues at vm/Thread.c