[kaffe] frustrating news regarding the pthread instability

Noa Resare noa at resare.com
Tue Oct 19 13:07:23 PDT 2004


Now I'm back from a few days away visiting my parents and I have
continued my investigation on the pthread instability in kaffe.

What I have concluded is sadly not what I had hoped for. I was looking
for a change in the pthread code somewhere between today and 1.1.4 that
introduced the lockups that I have been experiencing. However, it seems
like a simple test can "break" every version back to 1.1.4 given enough
time. What I have been chasing has always turned out to be unrelated to
threading in any other way than changing the timing and making the race
turn up more or less likely.

The test I am using is the following:

(ThreadState is ThreadState.java from tests/regression in cvs HEAD with
the timeout thread commented out.)

while true; do /tmp/kaffe-1.1.4/bin/kaffe  ThreadState || break;  date;
sleep 0.1; done

head cvs lasts about 5 minutes of this. 1.1.4 an hour or two other
versions in between probably about 10 minutes.

I'm giving up on this approach now and instead I'll be trying to find
the "fastest possible" way of producing a lockup in head cvs by
artificially change the timing and when I have something that is
reasonably fast (hopefully a few seconds) I'll try to analyze exactly
what happens.

but that will be tomorrow.. any input is of course appreciated.


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