Re: Deadlock in +initialize with libojbc2

[David Chisnall]

I think this should be fixed in trunk now, please let me know if it actually 
works...

David

On 5 Nov 2012, at 11:14, Tom Davie wrote:

> Just a quick heads up – I'm still experiencing this deadlock in version 1.6.1 
> of the runtime.  It can still be fixed by locking the runtime before locking 
> the initialise lock in objc_send_initialize.
> 
> Tom Davie
> 
> On 13 Aug 2012, at 11:26, Thomas Davie <address@hidden> wrote:
> 
>> I've done some reading through the source for libobjc2, and added a quick 
>> and dirty hack to lock the runtime in objc_send_initialize, as thread 1 was 
>> locking initialize lock then runtime lock while thread 2 was locking runtime 
>> lock then initialize lock... I though do not understand in any way how the 
>> threading model of libojbc2 works, so I probably did something pretty dumb 
>> in doing that.
>> 
>> I'd appreciate it if someone with knowledge of how threading is meant to 
>> work here could take a look at that and see if what I did was sane.
>> 
>> Thanks
>> 
>> Tom Davie
>> 
>> On 13 Aug 2012, at 10:11, Thomas Davie <address@hidden> wrote:
>> 
>>> Hi all,
>>> 
>>> I'm hitting an issue with deadlocks in +initialize.  I'm using the latest 
>>> (svn 35399) libobjc2.  Gdb tells me this:
>>> 
>>> (gdb) info threads
>>> Id   Target Id         Frame 
>>> * 2    Thread 0x7fffe2612700 (LWP 8878) "bds" 0x00007ffff65f9be4 in 
>>> __lll_lock_wait () from /lib/x86_64-linux-gnu/libpthread.so.0
>>> 1    Thread 0x7ffff7fe6000 (LWP 8875) "bds" 0x00007ffff65f9be4 in 
>>> __lll_lock_wait () from /lib/x86_64-linux-gnu/libpthread.so.0
>>> (gdb) thread 1
>>> [Switching to thread 1 (Thread 0x7ffff7fe6000 (LWP 8875))]
>>> #0  0x00007ffff65f9be4 in __lll_lock_wait () from 
>>> /lib/x86_64-linux-gnu/libpthread.so.0
>>> (gdb) bt
>>> #0  0x00007ffff65f9be4 in __lll_lock_wait () from 
>>> /lib/x86_64-linux-gnu/libpthread.so.0
>>> #1  0x00007ffff65f5200 in _L_lock_928 () from 
>>> /lib/x86_64-linux-gnu/libpthread.so.0
>>> #2  0x00007ffff65f5099 in pthread_mutex_lock () from 
>>> /lib/x86_64-linux-gnu/libpthread.so.0
>>> #3  0x00007ffff6a96919 in create_dtable_for_class (class=0x7fffdc862900, 
>>> root_dtable=0xae4ab0) at dtable.c:498
>>> #4  0x00007ffff6a964b9 in objc_send_initialize (object=<optimized out>) at 
>>> dtable.c:693
>>> #5  0x00007ffff6a9e776 in objc_msg_lookup_internal (receiver=<optimized 
>>> out>, selector=<optimized out>, sender=<optimized out>) at sendmsg2.c:73
>>> #6  objc_msg_lookup_sender (receiver=<optimized out>, selector=<optimized 
>>> out>, sender=<optimized out>) at sendmsg2.c:171
>>> #7  0x00000000005a4678 in -[Move 
>>> initWithAttack:withSoldier:againstTile:rolls:preAttackHP:preAttackPositions:preAttackBuffs:defenders:]
>>>  (self=0x7fffdc862878, _cmd=0x9b5770, a=0x28e5908, s=0x2e0e478, 
>>> #8  A bunch of my code all the way down to main.
>>> (gdb) thread 2
>>> [Switching to thread 2 (Thread 0x7fffe2612700 (LWP 8878))]
>>> #0  0x00007ffff65f9be4 in __lll_lock_wait () from 
>>> /lib/x86_64-linux-gnu/libpthread.so.0
>>> (gdb) bt
>>> #0  0x00007ffff65f9be4 in __lll_lock_wait () from 
>>> /lib/x86_64-linux-gnu/libpthread.so.0
>>> #1  0x00007ffff65f5200 in _L_lock_928 () from 
>>> /lib/x86_64-linux-gnu/libpthread.so.0
>>> #2  0x00007ffff65f5099 in pthread_mutex_lock () from 
>>> /lib/x86_64-linux-gnu/libpthread.so.0
>>> #3  0x00007ffff6a95fb8 in dtable_for_class (cls=<optimized out>, 
>>> cls=<optimized out>, cls=<optimized out>) at ./dtable.h:66
>>> #4  classHasDtable (cls=<optimized out>, cls=<optimized out>, 
>>> cls=<optimized out>) at ./dtable.h:110
>>> #5  mergeMethodsFromSuperclass (super=0x7ffff7d1a8e0, cls=<optimized out>, 
>>> methods=0x65ea8f0) at dtable.c:444
>>> #6  0x00007ffff6a9628d in add_method_list_to_class (cls=0x7ffff7d1a8e0, 
>>> list=<optimized out>) at dtable.c:488
>>> #7  0x00007ffff6a9aaa6 in class_addMethod (cls=0x7ffff7d1a8e0, 
>>> name=<optimized out>, imp=0x7ffff77eac30 <-[NSGDate 
>>> timeIntervalSince1970]>, types=<optimized out>) at runtime.c:191
>>> #8  0x00007ffff794ec4f in GSObjCAddMethods (cls=0x7ffff7d1a8e0, 
>>> list=0x65ea7a0, replace=0 '\000') at GSObjCRuntime.m:559
>>> #9  0x00007ffff794f566 in GSObjCAddClassBehavior (receiver=0x7ffff7d1a8e0, 
>>> behavior=0x7ffff7d1a810) at GSObjCRuntime.m:902
>>> #10 0x00007ffff77eb116 in +[GSDateSingle initialize] (self=0x7ffff7d1a8e0, 
>>> _cmd=<optimized out>) at NSDate.m:1517
>>> #11 0x00007ffff6a965c6 in objc_send_initialize (object=<optimized out>) at 
>>> dtable.c:733
>>> #12 0x00007ffff6a96427 in objc_send_initialize (object=<optimized out>) at 
>>> dtable.c:666
>>> #13 0x00007ffff6a9e776 in objc_msg_lookup_internal (receiver=<optimized 
>>> out>, selector=<optimized out>, sender=<optimized out>) at sendmsg2.c:73
>>> #14 objc_msg_lookup_sender (receiver=<optimized out>, selector=<optimized 
>>> out>, sender=<optimized out>) at sendmsg2.c:171
>>> #15 0x00007ffff77e975b in +[NSDate distantFuture] (self=0x7ffff7d1a740, 
>>> _cmd=<optimized out>) at NSDate.m:985
>>> #16 0x00007ffff78af10d in +[NSRunLoop initialize] (self=0x7ffff7d5fc40, 
>>> _cmd=<optimized out>) at NSRunLoop.m:697
>>> #17 0x00007ffff6a965c6 in objc_send_initialize (object=<optimized out>) at 
>>> dtable.c:733
>>> #18 0x00007ffff6a9e776 in objc_msg_lookup_internal (receiver=<optimized 
>>> out>, selector=<optimized out>, sender=<optimized out>) at sendmsg2.c:73
>>> #19 objc_msg_lookup_sender (receiver=<optimized out>, selector=<optimized 
>>> out>, sender=<optimized out>) at sendmsg2.c:171
>>> #20 0x00000000004aa888 in -[DatabaseConnection runPingThread] 
>>> (self=0x2a06698, _cmd=0x9b76b0) at Classes/Database/DatabaseConnection.m:120
>>> #21 0x00007ffff786a655 in -[NSObject performSelector:withObject:] 
>>> (self=<optimized out>, _cmd=<optimized out>, aSelector=0x9b76b0, 
>>> anObject=0x7fffe2610500) at NSObject.m:2001
>>> #22 0x00007ffff78e336e in -[NSThread main] (self=0x2a1c5b8, _cmd=<optimized 
>>> out>) at NSThread.m:741
>>> #23 0x00007ffff78e3b05 in nsthreadLauncher (thread=0x2a1c5b8) at 
>>> NSThread.m:807
>>> #24 0x00007ffff65f2efc in start_thread () from 
>>> /lib/x86_64-linux-gnu/libpthread.so.0
>>> #25 0x00007ffff632d59d in clone () from /lib/x86_64-linux-gnu/libc.so.6
>>> #26 0x0000000000000000 in ?? ()
>>> 
>>> Does anyone have any idea why this might be happening?
>>> 
>>> Thanks
>>> 
>>> Tom Davie
>>> _______________________________________________
>>> Discuss-gnustep mailing list
>>> address@hidden
>>> https://lists.gnu.org/mailman/listinfo/discuss-gnustep
>> 
> 
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