On Fri, Mar 11, 2011 at 2:36 AM, Quincey Morris <quinceymor...@earthlink.net> wrote: > On Mar 9, 2011, at 16:33, Jeffrey Walton wrote: > > The > code executes properly on the first invocation, but crashes on the > second invocation. The cause of the crash is walker = [fileManager > enumeratorAtPath:directory]. > > You should post the error message and the backtrace at the time of the > crash. "Crash" means different things in different contexts. OK. In the future, is 'bt full' preferred?
> Any ideas on the cause? I experience the crash with both methods of > retrieving the file manager. Are there known issues with > enumeratorAtPath? > > No. Your symptoms, as far as they can be analyzed in the absence of specific > information, sound like a memory management problem. The point at which the > crash occurs is where the error was detected, not (necessarily) where the > error really occurred. > > directory = [NSHomeDirectory() > stringByAppendingPathComponent:@"Documents"]; > walker = [fileManager enumeratorAtPath:directory]; > while((file = [walker nextObject]) != nil) > > That's three objects you don't take ownership of after they're handed to > you. I'd suggest starting by retaining them and releasing them before > exiting from this piece of code. You can't assume they're autoreleased when > handed to you (unless the documentation says so), and even then it's living > dangerously to avoid retaining them when something allocation-heavy like > directory enumeration is in progress. > [This is not a garbage collected app, is it? If so, then the answer is > different.] OK. Thanks. > According to 'NSFileManager Class Reference' > (http://developer.apple.com/library/mac/#documentation/Cocoa/Reference/Foundation/Classes/NSFileManager_Class/Reference/Reference.html): > > In iOS and Mac OS X v 10.5 and later you should consider > using [[NSFileManager alloc] init] rather than the singleton > method defaultManager. Instances of NSFileManager are > considered thread-safe when created using > [[NSFileManager alloc] init]. > > Some time back, an expert from Apple said that this documentation isn't > exactly correct. IIRC, there is [no longer, at least] anything special about > [NSFileManager defaultManager] -- except, I suppose, that it's a singleton, > so should only be used by a single thread at one time. '[[NSFileManager > alloc] init]' produces unique instances that should also be used by a single > thread at one time. IOW, more or less, each thread should use its own > NSFileManager instance. That's the only restriction. > Also, IIRC, none of the individual instances is thread safe in the sense > that it can be used by multiple threads at the same time. [The thread > safety, I assume, comes from the ability to have multiple instances working > at the same time, accessing a shared file system, which something quite > different.] > But I'm saying all this from imperfect memory, so I might have it wrong. OK - thanks. Do you have any recommendations on Mac OS X internals? In the Windows world, I have Richter's 'Advanced Windows' series, and Russinovich (et al) 'Windows Internals'. Great references that have saved me more than once. Jeff _______________________________________________ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
