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Re: Time Problem with NSThread
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Re: Time Problem with NSThread


  • Subject: Re: Time Problem with NSThread
  • From: Wayne Anderson <email@hidden>
  • Date: Fri, 30 Dec 2005 14:58:22 -0700

I tried setting the priority to max, [ NSThread setThreadPriority: 1.0 ]. This does not seem to help.

Again, the preferred solution would seem to be to take steps to make our app insensitive to thread timing jitter. But 100 ms. seems like a long time for a thread to be blocked even for a low priority thread.

Wayne

On Dec 30, 2005, at 1:42 PM, Jeff Moore wrote:

This sounds like your work thread is getting out competed by other threads on the system. What priority are you giving it?

On Dec 30, 2005, at 11:25 AM, Wayne Anderson wrote:

Our app currently is using an NSThread to run a timing loop that gets events from a Music Sequence. These events are then passed on to an internal processor that fills an internal buffer with samples. The Core Audio render thread then draws from this buffer on each render call. This scheme works fine on a dual processor G5 but on a 1.67 MHz PowerBook our internal NSThread occasionally gets blocked for a very long time (long in computer terms at least) on the order of 100 milliseconds. The block always seems to coincide with the Core Audio render thread grabbing processor time. The only thing we are doing on the render thread is calling memcpy to move data to the supplied ABL. Setting the priority on the NSThread seems to make no difference.

Is this kind of long blocking behavior normal?

Should we resort to a posix thread, or should we make use of ring buffers or some other construct to process our events ahead of time to make the app insensitive to this kind of thread timing jitter.


--

Jeff Moore
Core Audio
Apple


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References: 
 >Time Problem with NSThread (From: Wayne Anderson <email@hidden>)
 >Re: Time Problem with NSThread (From: Jeff Moore <email@hidden>)

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