Re: Thread question

[Banlu Kemiyatorn]

On Wed, Mar 2, 2011 at 1:24 PM, Richard Frith-Macdonald
<address@hidden> wrote:
>
> On 2 Mar 2011, at 06:21, Richard Frith-Macdonald wrote:
>
>
>>
>> OK ... that should build and run for you (and does for me) without trouble.
>> If it usually works, but fails, rarely, I guess there might be some race 
>> condition in gnustep-base (but from looking at the source I can't see how 
>> that could be).
>> If it fails consistently, I think there is something wrong with locking or 
>> threading on your machine.
>
>
> Of course, the best thing you can do is run under gdb, set a breakpoint to 
> catch the exception, and try to see where/how things are going wrong.

#0  -[NSRecursiveLock unlock] (self=0xb580a3b0, _cmd=0xb7fb5808) at NSLock.m:270
#1  0xb7d9b623 in +[NSUserDefaults standardUserDefaults]
(self=0xb7fb5700, _cmd=0xb7fb57f0)
    at NSUserDefaults.m:691
#2  0xb7d9b81b in GSPrivateDefaultsFlag (type=GSLogSyslog) at
NSUserDefaults.m:2144
#3  0xb7ce6a95 in NSLogv (format=0x804a23c,
    args=0xb615a264
"��\004\b[�ȷ�_��\b�\004\bl�\004\b��\004\b(�\b\b��\004\b\b�\004\b�\210\004\b�_��\b�\004\b\020z\a\b��\025�0�Ϸ\020z\a\b\b�\004\b")
at NSLog.m:305
#4  0xb7ce6f04 in NSLog (format=0x804a23c) at NSLog.m:252
#5  0x08048922 in -[MyObj launch:] (self=0x8077a10, _cmd=0x804a208,
task=0x0) at problem.m:24
#6  0xb7cfdb30 in -[NSObject performSelector:withObject:]
(self=0x8077a10, _cmd=0xb7fa5da8,
    aSelector=0x804a208, anObject=0x0) at NSObject.m:1763
#7  0xb7d6bc6a in -[NSThread main] (self=0x808df10, _cmd=0xb7fa5db0)
at NSThread.m:729
#8  0xb7d6c291 in nsthreadLauncher (thread=0x808df10) at NSThread.m:792
#9  0xb7b36cc9 in start_thread () from /lib/libpthread.so.0
#10 0xb7a4569e in clone () from /lib/libc.so.6

Above is what I got from bt, below is the code that cause the problem
which, commenting out any NSLog will put away the "Uncaught exception
NSLockException, reason: failed to unlock mutex" problem.

#include <unistd.h>
#import <Foundation/Foundation.h>

@implementation NSObject (Launch)
- (void) launch:(id)task
{
        id p = [NSAutoreleasePool new];
        NSLog(@"hello");
        [p release];
}
@end

int main (int argc, const char * argv[]) {
        [NSAutoreleasePool new];
        id obj = [NSObject new];
        [NSThread detachNewThreadSelector:@selector(launch:)
toTarget:obj withObject:nil];
        NSLog(@"failing");
        [NSThread detachNewThreadSelector:@selector(launch:)
toTarget:obj withObject:nil];
        return 0;
}