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Re: AudioDeviceStop and ioProc
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Re: AudioDeviceStop and ioProc


  • Subject: Re: AudioDeviceStop and ioProc
  • From: Jeff Moore <email@hidden>
  • Date: Tue, 23 May 2006 14:20:39 -0700

As Bill says, the command line version is definitely the way to go. It even has a pretty good man page to help you out.

At any rate, the new backtraces you put in the previous email work out like this:

- Thread 2 appears to be the the main thread. It is blocked making a call to AudioDeviceStop(). The lock it is blocked on is definitely the IO thread lock.

- Thread 3 appears to be the HAL's notification thread. It is also blocked trying to lock the IO thread lock, probably because it is fielding a notification from the driver. The other back trace for this thread shows the thread in it's normal, quiet state.

- Thread 5 appears to be an IO thread. It is not blocked. Rather, it is in a system call that maps a pthread ID to a mach thread ID so that the HAL can change the thread into a time constraint thread. Being a running IO thread, this thread is holding the lock that the other two threads are blocked on.

This information is inconclusive. It looks to me like all the HAL threads are functioning normally. The IO thread is not blocked, so it will eventually let go of the lock which will unblock the other threads. I imagine that there are other threads in this process. I would need to see what those threads are doing to be able to diagnose the hang further.

BTW, these back traces are classic examples of why an instantaneous look at the stacks is not really that helpful when trying to diagnose a hang. To an untrained eye, thread 5 might looked blocked. It isn't, but the only way to know that is to do what the sample tool does: take snapshots of the stacks over time. This would show that this thread has many different back traces because it is still running.

On May 23, 2006, at 11:14 AM, William Stewart wrote:

Try this from the command line:

% sample <PID> <duration in secs>

You can just type sample and get a list of options.

Bill

On 22/05/2006, at 11:01 PM, Steve Checkoway wrote:


On May 22, 2006, at 10:34 PM, Steve Checkoway wrote:
I'm going to reinstall the dev tools to see if I can get Sampler to work.

No luck. The private framework it requires was not installed. I'll ask on the Xcode-users list.


--

Jeff Moore
Core Audio
Apple


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  • Follow-Ups:
    • Re: AudioDeviceStop and ioProc
      • From: Steve Checkoway <email@hidden>
References: 
 >Re: AudioDeviceStop and ioProc (From: "B.J. Buchalter" <email@hidden>)
 >Re: AudioDeviceStop and ioProc (From: Jeff Moore <email@hidden>)
 >Re: AudioDeviceStop and ioProc (From: Steve Checkoway <email@hidden>)
 >Re: AudioDeviceStop and ioProc (From: Jeff Moore <email@hidden>)
 >Re: AudioDeviceStop and ioProc (From: Steve Checkoway <email@hidden>)
 >Re: AudioDeviceStop and ioProc (From: Jeff Moore <email@hidden>)
 >Re: AudioDeviceStop and ioProc (From: Steve Checkoway <email@hidden>)
 >Re: AudioDeviceStop and ioProc (From: Steve Checkoway <email@hidden>)
 >Re: AudioDeviceStop and ioProc (From: William Stewart <email@hidden>)

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