[M3devel] wrapping postgresql library not enough

[Tony Hosking]

If you are able to get the debugger to stop there then you should still be able to dump the threads from the debugger:

call ThreadPosix__DumpEverybody()

Antony Hosking | Associate Professor | Computer Science | Purdue University
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On Apr 20, 2011, at 11:20 PM, Mika Nystrom wrote:

> Aha, I will try that if it happens again.  I wrapped more things that I think
> might be iffy in my program.
> 
> But I have a feeling ThreadPosix__DumpEverybody won't work... the
> application is probably deadlocked by having a single thread locking
> against itself with some sort of pthread lock.  I should look at the
> source code of free.
> 
>     Mika
> 
> Tony Hosking writes:
>> Can you dump all the user threads at this point?  =
>> ThreadPosix__DumpEverybody() should do it.  We want to see where the =
>> other threads might be.
>> 
>> On Apr 20, 2011, at 10:53 PM, Mika Nystrom wrote:
>> 
>>> Hi again,
>>> =20
>>> So, as I described before, I wrote a program that wraps all of =
>> Critical
>>> Mass's "postgresql" library (PQ.i3) with Scheduler.DisableSwitching /
>>> Scheduler.EnableSwitching.  Yes, it seems to have reduced the =
>> frequency
>>> at which my application locks up, but it has not eliminated the =
>> lockups.
>>> =20
>>> User threads, AMD64_LINUX.
>>> =20
>>> I'm not quite sure what to try next.  How can I find out where malloc
>>> and free might be used reentrantly, assuming that is the problem?
>>> =20
>>> There may not be any reliable threading in CM3 anymore.  Possibly it's
>>> reliable on FreeBSD (without -pthread) but I wouldn't bet money on it.
>>> =20
>>>    Mika
>>> =20
>>> (gdb) where
>>> #0  0x00007f7a8da0102e in ?? () from /lib/libc.so.6
>>> #1  0x00007f7a8d99eb43 in ?? () from /lib/libc.so.6
>>> #2  0x00007f7a8d99baab in free () from /lib/libc.so.6
>>> #3  0x000000000077b08d in PQsendQuery ()
>>> #4  0x0000000000767c12 in PQSchedulerWrap__PQsendQuery (conn=3DCannot =
>> access memory at address 0x7f7b848a4298
>>> )
>>>   at ../AMD64_LINUX/PQSchedulerWrap.m3:210
>>> #5  0x0000000000763ce0 in UnsafeDatabase__MyExec (t=3DCannot access =
>> memory at address 0x7f7b848a4328
>>> ) at ../src/UnsafeDatabase.m3:92
>>> #6  0x0000000000764a29 in UnsafeDatabase__ExecM (t=3DCannot access =
>> memory at address 0x7f7b848a43f8
>>> ) at ../src/UnsafeDatabase.m3:239
>>> #7  0x0000000000764cee in UnsafeDatabase__TExecM (t=3DCannot access =
>> memory at address 0x7f7b848a4528
>>> ) at ../src/UnsafeDatabase.m3:269
>>> #8  0x0000000000756638 in DesynchronizedDB__TransSExec (trans=3DCannot =
>> access memory at address 0x7f7b848a45e8
>>> ) at ../src/DesynchronizedDB.m3:74
>>> #9  0x00000000005aeac6 in =
>> DBTable_gcoms_ordr_statusMonitor__ScanDirty__Attempt.1014 =
>> (finalAttempt=3DCannot access memory at address 0x7f7b848a463f
>>> )
>>>   at ../AMD64_LINUX/DBTable_gcoms_ordr_statusMonitor.m3 =3D> =
>> /home/mika/t/calarm/ratsql/src/TableMonitor.mg:41
>>> #10 0x00000000005ae639 in DBTable_gcoms_ordr_statusMonitor__ScanDirty =
>> (cl=3DCannot access memory at address 0x7f7b848a4778
>>> )
>>>   at ../AMD64_LINUX/DBTable_gcoms_ordr_statusMonitor.m3 =3D> =
>> /home/mika/t/calarm/ratsql/src/TableMonitor.mg:73
>>> #11 0x00000000005b171e in =
>> DBTable_gcoms_ordr_statusMonitor__CheckForNew (cl=3DCannot access memory =
>> at address 0x7f7b848a4958
>>> )
>>>   at ../AMD64_LINUX/DBTable_gcoms_ordr_statusMonitor.m3 =3D> =
>> /home/mika/t/calarm/ratsql/src/TableMonitor.mg:469
>>> #12 0x00000000005b1382 in DBTable_gcoms_ordr_statusMonitor__Sync =
>> (cl=3DCannot access memory at address 0x7f7b848a4ba8
>>> )
>>>   at ../AMD64_LINUX/DBTable_gcoms_ordr_statusMonitor.m3 =3D> =
>> /home/mika/t/calarm/ratsql/src/TableMonitor.mg:445
>>> #13 0x00000000005b0e1c in DBTable_gcoms_ordr_statusMonitor__ApplyC =
>> (cl=3DCannot access memory at address 0x7f7b848a4d58
>>> )
>>>   at ../AMD64_LINUX/DBTable_gcoms_ordr_statusMonitor.m3 =3D> =
>> /home/mika/t/calarm/ratsql/src/TableMonitor.mg:393
>>> #14 0x0000000000922eb5 in ThreadPosix__RunThread () at =
>> ../src/thread/POSIX/ThreadPosix.m3:1174
>>> #15 0x00007f7a8d9697b0 in ?? () from /lib/libc.so.6
>>> #16 0x0000000000000000 in ?? ()
>>> (gdb)=20