[rvm-research] wait/notify(All) question

[albert n. <nol...@gm...>]

Hi,

I have a question concerning the wait/notify(All) implementation in the most
recent version of JikesRVM (3.1.1).

1) How can it be that the lock is zero when notifyAll in RVMThread.java is
invoked? According to the JLS, the calling thread must own the lock.

here is the code snippet from RVMThread,java:
...
       Lock l = ObjectModel.getHeavyLock(o, false);
       if (l == null)
          return;
...

2) In the function waitImpl in RVMThread.java:
  a) What is the purpose if the field?
         ...
         protected Object waitObject;
         ...
     It is written twice but never read.
  b) How can it be possible that after a thread is woken up (from the wait
method) that the object on which the thread waited has
      no associated lock with it? I am just asking because the second
parameter (see below) is set to true.
            ... // from wiatImpl in RVMThread.java
            if (waitCount != 1) { // reset recursion count
                Lock l2 = ObjectModel.getHeavyLock(o, true);
                l2.setRecursionCount(waitCount);
            }
            ...

I want to make sure that I understand the wait/notify implementation in
Jikes, since I am currently trying to find a bug. A thread waits on an
object A, however, although calling notifyAll on the same object does not
wake up the waiting thread.

Many thanks for your help.

Cheers,
Albert