Re: An acutal NSLock bug

[Adam Fedor]

On 2005-10-20 12:56:22 -0600 Morgan Giddings <giddings@unc.edu> wrote:

> 
> numprocesses=99;
> while (numprocesses >= 0) {
>     [myLock lock];
>     [NSThread detachNewThreadSelector:@selector(doProcess:)  
> toTarget:anObject 
> withObject:anotherObject];
>     numprocesses --;
> }
> 


Well, I think you are still using an undocumented feature of the locking code. 
For instance, the Apple documentation has this to say:

Important:  Many mutex locking mechanisms are designed to return an error if a 
thread tries to acquire a mutex it already owns. Such an action could deadlock 
the thread and should be avoided. If your thread needs to acquire the same lock 
multiple times, you should use a recursive lock, as described in “Recursive 
Locks”.

http://developer.apple.com/documentation/Cocoa/Conceptual/Multithreading/index.html#//apple_ref/doc/uid/10000057i


That being said, I could see how this type of usage could be beneficial. 
Although I do not know if the underlying thread mechanism supports this.  I 
would suspect Condition Locks to be better used here (Unfortunately, GNUstep 
has the same limitation with NSConditonLock locks, which I am definitely more 
inclined to change, if it is possible using the underlying thread mechanism).