OS X. It happens in all circumstances.
-- Seth Willits > On May 22, 2016, at 10:59 AM, Alex Zavatone <z...@mac.com> wrote: > > Mac, iOS? If iOS, device or sim? IPad? > > Try publishing and not running through Xcode. > > Sent from my iPhone > >> On May 22, 2016, at 12:48 PM, Seth Willits <sli...@araelium.com> wrote: >> >> I'm thoroughly confused and increasingly desperate. *All* of the threads in >> my application periodically are blocked for 30-50 ms pretty regularly, about >> every 150 ms. >> >> I'm processing a bunch of data via NSOperations running in a couple of >> "serial" (maxConcurrentOperationCount = 1) NSOperationQueues. Each of the >> operations is itself synchronous (overriding -main). Everything works as >> expected. For performance reasons, I want to move one of the operation types >> to being asynchronous and eventually allow two concurrent operations. >> >> So to start with, I took the synchronous code in -main, moved it into >> -start, and added the appropriate KVO notifications for isExecuting, >> isFinished, and implemented the right accessors etc. So effectively the >> operation says it's asynchronous, but all of its work is actually done in >> -start, followed by notifying it's finished. The work is all done correctly, >> but I noticed it took significantly longer to complete. >> >> Thankfully I have a nifty bit of debugging code which tracks the start and >> ends of each of these operations and visualizes them, and this is what I >> noticed: >> http://www.sethwillits.com/temp/upshot/upshot_yJutoKqY.png >> >> At very regular intervals everything takes longer. >> >> First I thought it maybe didn't like my semi-async op, so I made it truly >> async, and it behaved exactly the same. To make a long story short, I looked >> at this a few different ways in Instruments, and have confirmed that what's >> actually happening is *every thread is blocked* for those 30-50ms, and then >> it just wakes up and everything continues. The threads are literally all in >> "Blocked" states. >> >> >> I can't figure out *why* everything is blocked. I can't figure out why >> simply making the NSOperation asynchronous would have this crazy effect. >> It's 100% reproducible. >> >> For what it's worth, this one particular operation is doing some Metal >> rendering, and that operation is blocked during a call to >> -waitUntilCompleted. Which yes, sound suspicious, but is exactly what's >> happening in the very-explicitly-synchronous version of the operation, and >> it takes 10x less time. I am pretty certain this has nothing to do with the >> Metal rendering itself, and has more to do with something confusing the >> dispatch manager and every thread is being blocked. >> >> >> Can anyone think of what I should look for to figure out *why* they're >> blocked? Looking at the system calls in the Instruments trace timeline just >> isn't telling *me* anything. >> >> >> -- >> Seth Willits >> _______________________________________________ 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
