[M3devel] cm3 pthread problem?... another one?

[Tony Hosking]

It is a pthreads call that is failing:

           WITH r = Upthread.kill(act.handle, SIG_SUSPEND) DO
             <*ASSERT r=0*>
           END;

I'm guessing we are in a race with a thread that is in the middle of  
dying (i.e., the error code, "r", is "ESRCH: thread is an invalid  
thread ID").  Can you confirm that is the error?

As for why it is happening I don't know, since the thread handle is  
only ever accessed while activeMu is locked, which enforces atomicity  
of the thread's presence in the ring of live threads along with its  
handle being valid:

     WITH r = Upthread.mutex_lock(activeMu) DO <*ASSERT r=0*> END;
       IF allThreads = me THEN allThreads := me.next; END;
       me.next.prev := me.prev;
       me.prev.next := me.next;
       me.next := NIL;
       me.prev := NIL;
       WITH r = Upthread.detach(me.handle) DO <*ASSERT r=0*> END;
     WITH r = Upthread.mutex_unlock(activeMu) DO <*ASSERT r=0*> END;

I wonder if this is a system limit on the number of threads or some  
such (but then why would the pthread_create call not return an  
error?)  Can you diagnose further?

On Apr 22, 2007, at 5:12 AM, Dragiša Durić wrote:

>   After upping it a bit, with stack limit set to 64k and 4000  
> threads in
> each loop... Is not happening at same place every run, but most of  
> runs
> - it happens.
>
> Forking 4000 threads... (1)
> Forked.
> ,:
>
> ***
> *** runtime error:
> ***    <*ASSERT*> failed.
> ***    file "../src/thread/PTHREAD/ThreadPThread.m3", line 1083
> ***
>
>
> On Sat, 2007-04-21 at 10:48 -0400, Tony Hosking wrote:
>> I have fixed this bug and checked in the fix to CVS (why are we not
>> seeing the commit messages again?).  It did turn out to be a deadlock
>> issue in the handshake between allocating threads and the GC.  Your
>> sample program now runs with no problems on my dual-core Intel Mac.
>> Please let me know if you have any other threading difficulties.
>>
>> Regards,
>>
>> Tony
>>
>> On Apr 20, 2007, at 8:21 AM, Dragiša Durić wrote:
>>
>>> Attached program won't run under freshly built cm3 @ Fedora Core 6.
>>> Compiles, runs... and stucks...
>>>
>>> It works flawlessly with user-level threads and also with mine
>>> implementation of NPTL for pm3. I've done it for 4000 threads per
>>> 10000
>>> passess, and this version I am attaching, and trying without
>>> success on
>>> CM3 is 40 threads...
>>>
>>> Of course, before I run it, I am ulimiting stack size to 64kB or
>>> similar.. It fits.
>>>
>>> dd
>>> -- 
>>> Dragiša Durić <dragisha at m3w.org>
>>>
>>> _______________________________________________
>>> M3devel mailing list
>>> M3devel at elegosoft.com
>>> https://mail.elegosoft.com/cgi-bin/mailman/listinfo/m3devel
>>
> -- 
> Dragiša Durić <dragisha at m3w.org>