Re: Thread issue - sure can use some help
Re: Thread issue - sure can use some help
- Subject: Re: Thread issue - sure can use some help
- From: Jeff Moore <email@hidden>
- Date: Thu, 6 Apr 2006 12:29:28 -0700
The crash looks to me like your thread is trying to message a bad
ObjC object. That implies some kind of data coherency issue in your
code. My guess is that you have one thread that is disposing of an
object while another thread is trying to use it.
The hang is a deadlock of some flavor. This means that one thread is
blocking while holding onto a lock that is blocking the other thread
while it tries to acquire the lock.
Both problems are pretty basic parallel programming problems that
unfortunately, have no set answers. The solution is going to be
totally driven by the context. You need to look very closely at how
the various threads interact with your data and design a locking
solution that ensures that things like this don't happen while at the
same time allowing the code to still be able to satisfy the real time
demands of the audio system (ie. make the deadlines and don't block
the IO thread, ever).
On Apr 6, 2006, at 3:23 AM, John Draper wrote:
Hi,
I've also CC'ed this to both Core Audio and the Multi-processing
list, in the
hopes that someone can give me a clue on what's going on.
First the forplay...
* Using a C++ library (JRTPLIB) a real time transport for VIOP
packets, which
uses it's own thread. This thread is not an NSThread, and I
have my application
running in Multi-processing mode, so I can make Autorelease
pools for this thread
and others.
* This thread calls methods in MTCoreAudio, an Obj C wrapper
around the
lower level Core Audio. This is available on the net from 3rd
party.
* Program will either hang up in the Mutex.lock() part of the
thread in
question above, or crash....
Crash log here....
Thread 6 Crashed:
0 libobjc.A.dylib 0x908311e8 objc_msgSend + 0x8
1 com.apple.Foundation 0x90a06320 -
[NSConcreteMutableData appendData:] + 0x2c
2 com.apple.myCocoaApp 0x00023598 -[VIOPAudioMonitor
_flushDataForConverter:] + 0x100 (VIOPAudioMonitor.m:251)
3 com.apple.myCocoaApp 0x00023398 -[VIOPAudioMonitor
flushOutput:] + 0x7c (VIOPAudioMonitor.m:231)
4 com.apple.myCocoaApp 0x000237b4 -[VIOPAudioMonitor
queueAudioSampleData:] + 0x7c (VIOPAudioMonitor.m:274)
5 com.apple.myCocoaApp 0x00037f68 -[AudTransport
processIncomingData:] + 0x8c (AudTransport.m:76)
6 com.apple.myCocoaApp 0x0000c6ec -[RTPSessionBridge
incomingPacket:ofLength:] + 0x80 (RTPSessionBridge.mm:183)
7 com.apple.myCocoaApp 0x0000b788
MyRTPSession::ProcessRTPPacket(RTPSourceData const&, RTPPacket
const&) + 0x74 (myRTPSession.cpp:84)
8 com.apple.myCocoaApp 0x0000b6a0
MyRTPSession::OnPollThreadStep() + 0x17c (myRTPSession.cpp:55)
9 com.apple.myCocoaApp 0x001b5820 RTPPollThread::Thread
() + 0x254 (rtppollthread.cpp:158)
10 com.apple.myCocoaApp 0x001c9650 JThread::TheThread
(void*) + 0xac (jthread.cpp:152)
11 libSystem.B.dylib 0x900246e8 _pthread_body + 0x28
Since none of this stuff is secret (It's a SIP phone for the Mac),
I don't mind sharing the code
with anyone willing to help me out.
The SIP phone works now, but ONLY for about a minute then either
locks up or crashes, depending on
the phase of the moon, or topical strata :-)
The JThread basically receives UDP Packet data via the Posix
"recvfrom" API in "OnPollThreadStep"
which eventually calls ProcessPacket.
Through process elimination, I selectively commented out portions
of the code to try and
determine which one causes it to hang, and determined the
"[VIOPAudioMonitor queueAudioSampleData:]";
method is the culprit.
Can someone please tell me how I can make this code "Thread safe"
when it calls something
I know nothing about (MTCoreAudio framework).... the
"AudTransport" is a delegate of the
VIOPAudioMonitor, which is my AudioMonitor Delegate. Like I
said, if anyone is willing to help
me on this, I can send you the project, if you still use X-Code
1.5. yea - I know, I should
upgrade, and eventually hope to do so soon, but not until I can
afford to get a better machine
that will support OS-X 10.4...
I don't have the disk space to upgrade to 10.4 right now.
Can someone help me please?
John
_______________________________________________
Do not post admin requests to the list. They will be ignored.
Coreaudio-api mailing list (email@hidden)
Help/Unsubscribe/Update your Subscription:
This email sent to email@hidden
--
Jeff Moore
Core Audio
Apple
_______________________________________________
Do not post admin requests to the list. They will be ignored.
Coreaudio-api mailing list (email@hidden)
Help/Unsubscribe/Update your Subscription:
This email sent to email@hidden