Weird. My old code used to be GCD heavy and even deadlocked once but new projects that used old school methods are faster and never locked up. My projects are heavy in network IO.
I built a transactional network interface there, which is somehow a clone of Distributed Objects that is based on HTTP. Sent from my iPad > On Apr 27, 2014, at 5:36 AM, Jens Alfke <j...@mooseyard.com> wrote: > > >> On Apr 26, 2014, at 2:10 PM, ChanMaxthon <xcvi...@me.com> wrote: >> >> Since you are interfacing with database maybe you can use a little >> transaction interface which is its own thread and run loop. That may be able >> to cut down your amount of syscalls. That is, not using GCD but old >> fashioned NSThread, NSRunLoop (and CFRunLoop) and NSCondition. > > I’m pretty sure NSRunLoop has more overhead than a dispatch_queue does. It’s > doing more work and it’s using Obj-C messaging. > >> OS X implemented GCD at kernel level which introduced lots of syscalls which >> are super expensive. The old school method is largely user land so it may >> help a little by keeping syscalls to a minimum. @synchronized uses >> Objective-C runtime functions which was once code behind those old school >> classes. > > That's the opposite of what the docs say: "A dispatch semaphore works like a > traditional semaphore, except that when the resource is available, it takes > less time to acquire a dispatch semaphore. The reason is that Grand Central > Dispatch does not call into the kernel for this particular case. It calls > into the kernel only when the resource is not available and the system needs > to park your thread until the semaphore is signaled.” —Concurrency > Programming Guide > > —Jens _______________________________________________ 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: https://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
