On 17 Jul 2010, at 07:02, Kyle Sluder wrote: > On Fri, Jul 16, 2010 at 10:36 PM, Rafael Cerioli > <rafael.ceri...@gmail.com> wrote: >> I guess I had something wrong, NSURLConnection does not do anything in a >> background thread. It just operates in the main thread but "asynchronously" >> thanks to the run loop. > > Well, sort of. I believe what actually happens is that it uses a > private helper thread to perform the communication but notifies its > delegate on the main thread. But that's an implementation detail that > I might well have wrong. All that matters is that something gets > scheduled on the calling thread's runloop that is responsible for > notifying the delegate.
That is correct. The connection is scheduled on the current thread, but the actual protocol implementations all happen on a single shared thread. Implementation detail though; doesn't matter to vast majority of uses! > >> Quote from NSURLConnection class reference : >> "At creation, a connection is scheduled on the current thread (the one where >> the creation takes place) in the default mode" >> That means, there is a lot of work done in the main thread. Even if the >> connection is not scheduled in the runloop "tracking" mode (for the UI), I >> guess the app would slow down at some point. > > Guessing is not helpful. Start at the highest level of abstraction. If > you can demonstrate with actual data that it poses a problem, then > remove one layer of abstraction. Hear hear! > >> Isn't it better to use -[NSData initWithContentOfURL:] synchronous load >> method in background thread ?Or is there something wrong about that kind of >> use ? > > It uses NSURLDownload, which has had its own share of problems: > http://lists.apple.com/archives/Cocoa-dev/2007/Jun/msg00117.html Really? I'd be very surprised if this were the case. Why download the file to disk if it's wanted in memory anyway? > > In general, the answer to your Cocoa problems is not "spawn a thread." > >> By the way, I never seen any bug about NSURLConnection running in background >> threads on iPhone OS. > > See above, but also here for the exact backtrace: > http://lists.apple.com/archives/cocoa-dev/2008/May/msg03073.html > > Again, this may have been fixed, the whole asynchronous thing might be > a red herring for a more pervasive bug that also affects asynchronous > use of the API, or (miracle of miracles) the bugs may have been fixed. > But the received wisdom is do not use NSURLConnection synchronously, > especially since it doesn't really give you any benefit to start with. > > --Kyle Sluder > _______________________________________________ > > 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/cocoadev%40mikeabdullah.net > > This email sent to cocoa...@mikeabdullah.net _______________________________________________ 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
