Spin locks are useful in certain situations. First of all, on a single-processor system, it's never a good idea to use a spin lock because all it will do is burn up the waiting thread's scheduling quantum while preventing a thread that's holding the lock from getting scheduled so that it can complete its work and release the lock.
A spin lock is useful in multi-processor environments when you know that a lock will be held for a *very short period of time*. In this case, spin locks can help you avoid excessive context switching because a waiting thread will often be able to spin (do something else) while waiting for a lock to be released, acquire the lock, and do its work, all within its scheduling quantum. In many simple scenarios, especially when contention is very low, @synchronized will be the best choice because it's trivial to get right and high-performance. In other scenarios, a fair readers-writers lock will be ideal. On Thu, Mar 8, 2012 at 9:52 AM, Jan E. Schotsman <jesc...@xs4all.nl> wrote: > > On Mar 8, 2012, at 3:22 PM, CoGe - Tamas Nagy wrote: > > Maybe this will helps you, here is my thread-safe subclass of >> NSMutableArray: http://code.google.com/p/**cogeopensource/source/browse/* >> *trunk/CoGeOpenSource/**CoGeThreadSafeMutableArray.m<http://code.google.com/p/cogeopensource/source/browse/trunk/CoGeOpenSource/CoGeThreadSafeMutableArray.m> >> > > Thanks for the code. > I have two questions: > > 1. If you believe that OSSpinLock is faster than NSLock why don't you use > it for your thread-safe mutable array class too? > > 2. Once you start using an enumerator for the array you probably need a > explicit mutex after all. Isn't it simpler to just use > @synchronized(array) wherever the array is accessed? > > Jan E. > > ______________________________**_________________ > > 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<http://lists.apple.com> > > Help/Unsubscribe/Update your Subscription: > https://lists.apple.com/**mailman/options/cocoa-dev/** > brianlambert%40gmail.com<https://lists.apple.com/mailman/options/cocoa-dev/brianlambert%40gmail.com> > > This email sent to brianlamb...@gmail.com > _______________________________________________ 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
