Gang, I've encountered an odd bug/issue/feature(?) in Lion and want to know if there's a workaround available.
I have a multithreaded CoreData application. It does a lot of calculations on the context, so it spawns off a separate thread and creates a new ManagedObjectContext to do its work. AFAIK, I'm following proper Best Practices for multi-threaded core data access. This all works fine. The issue is, at the start of my thread, I call saveDocument: on the main context, in the main thread via this: [self performSelectorOnMainThread:@selector(saveDocument:) withObject:nil waitUntilDone:YES]; I didn't want to worry about jumping through the hoops of merging the contexts, so I just ensure the main context is clean and saved. It invokes saveDocument, then checks to see if the context still has changes, and if it does it bombs out and refuses to continue, assuming that the save failed for some reason. This works fine under Snow Leopard (and Leopard, and it used to work under Tiger as well, though I no longer support that OS). But under Lion, it fails since it doesn't actually wait until the save is complete. It looks like pre-Lion, saveDocument: would directly invoke the writeToURL:... method, whereas in Lion it's deferring it until the next invocation of the run loop. So under Snow Leopard, I'd see this behavior: SECOND THREAD: perform saveDocument on Main, wait until done MAIN THREAD: call saveDocument MAIN THREAD: call writeToURL:... SECOND THREAD: done waiting for main to complete, carry on. But now on Lion, I see this: SECOND THREAD: perform saveDocument on Main, wait until done MAIN THREAD: call saveDocument SECOND THREAD: done waiting for main to complete, carry on. Sees that the main MOC still has changes, fails out. MAIN THREAD: call writeToURL:... So Lion waits for saveDocument: to finish, but then writeToURL:... is called later. I have a simple test case to verify: http://www.prototypesite.net/threadedsavetest.zip If you run it on Lion, writeToURL is called after the second thread is done waiting. If you run it on Snow Leopard, it's done before. Is this a bug or a feature? If it's a feature and expected to behave this way, then what's the proper way for me to get this behavior now, in a way that's backwards compatible on Snow Leopard and Leopard? -Jim.... _______________________________________________ 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
