The memory pressure is caused by other apps on the user's machine. My test program just increments a counter when there is a glitch, and requires a trivial amount of memory. Yet, it can see glitches when other apps run in the background allocating memory.
Why wouldn't it be possible to mlock all the memory pages used by the real-time thread?
I do my best to do it on the application side. It would be nice if Apple's CoreAudio did the same.
If you mean that it is difficult to identify the pages used, that is true, but I found a great way to do just that. I keep track of all the pages I mlock(), list all the remaining pages, and mprotect them to crash if I accidentally access memory that was not mlocked. That helped me identify a couple of pages I forgot, such as the one that contains the __stack_chk_guard
And regarding the code pages, for some reason I get a permission denied error if I try to mlock them. Not sure why.
There is no mlockall() on macOS, but if there was one, I could delegate the real-time audio handling code to a separate executable, and call mlockall(). I would be guaranteed all the pages used by the real-time thread would be mlocked.
And by the way if you are interested in the report I sent to Apple, you can find all the details with the sample code to reproduce the problem there:
It contains a program where the only thing I do in the real-time callback is to count the glitches, and I made sure to mlock() the memory used by the glitch counting code. When the memory pressure increases, it glitches.
I have just reported a bug where high memory pressure could cause memory pages from the real-time audio thread to get swapped out, causing audio glitches. I am not hopeful for a timely resolution now...
TwistedWave, is an audio editor for macOS, iOS and Online, and I have almost finished porting it to Windows. I would appreciate any help in testing the Windows version before I release it officially.
I don't understand. In most of your samples, there is no bar in the first two bands. Does that mean that your samples are a multiple of 1 MB?
If your read/write rate is not constant, such as in the non-optimized file copy and you display the rate mod 1024 in the first band, I expect to see seemingly random bars that would not show any meaningful information. What am I missing?
Hey, I have also done an audio editor and recorder in the browser! All the audio is stored and processed on the server. You can Check it out there: https://twistedwave.com/online/
After making an OS X and an iOS version of TwistedWave, I have now made an Online version that works in a web browser.
All the audio is stored and processed on the server.
There is a small flash module used to record audio, but I will be happy to get rid of it as soon as we have a browser with support for the AudioWorkerNode.
I have also made an API so you can integrate it with your own web site.
Having list iterators carry a field pointing to their container wouldn't help you determine the number of objects between two iterators when you splice, which is what you need in order to maintain the object count.
Storing an index in the iterator would not be a solution either. That would mean updating the index in all the existing iterators when you insert an object in the list.