[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: Deadlock in +initialize with libojbc2
From: |
David Chisnall |
Subject: |
Re: Deadlock in +initialize with libojbc2 |
Date: |
Mon, 13 Aug 2012 15:41:47 +0100 |
The runtime follows the Apple semantics that +initialize uses a per-class lock.
If you hit a deadlock here, then most likely your code is wrong and won't work
on Apple's implementation either. The GCC runtime uses a single lock for all
+initialize instances, so will deadlock in a different set of situations.
David
On 13 Aug 2012, at 11:26, Thomas Davie 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 <tom.davie@gmail.com> 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
>> Discuss-gnustep@gnu.org
>> https://lists.gnu.org/mailman/listinfo/discuss-gnustep
>
>
> _______________________________________________
> Discuss-gnustep mailing list
> Discuss-gnustep@gnu.org
> https://lists.gnu.org/mailman/listinfo/discuss-gnustep
-- Sent from my PDP-11