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.da...@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 _______________________________________________ Discuss-gnustep mailing list Discuss-gnustep@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnustep
