Hi all,
I have a Mac OS X application running on 10.11 that sometimes hangs while
performing a network upload. The upload is performed over HTTPs using
NSURLConnection that has a bodyStream associated with it. The body stream is
one end of a CFStream created with CFStreamCreateBoundPair. The other end of
the stream is written to periodically as data becomes available. When I get an
NSStreamHasSpaceAvailable delegate message, I append the data I have available
in my stream.
This all works well 90% of the time, but around 1 in 20 uploads will deadlock
with the backtrace below. It looks like CFStream is calling my delegate
recursively—frames 10 and 4 are both in my delegate callback, for the same
stream, with the same event code (hasBytesAvailable). This in itself is weird,
but it causes a deadlock because boundPairWrite must be implemented with a
mutex that is taken recursively.
In frame 10, I write all the data I have at the moment—152 bytes. This isn’t
large, and doesn’t fill up the transfer size associated with the bound stream
(which is 4K at the moment). Best I can tell, CFStream decides that since I
didn’t consume all the space, it can send another hasBytesAvailable delegate
message.
Am I reading things wrong? Here’s the backtrace.
(lldb) thread backtrace all
* thread #1: tid = 0x82b0e1, 0x00007fff8ad8fee2
libsystem_kernel.dylib`__psynch_mutexwait + 10, queue =
'com.apple.main-thread', stop reason = signal SIGSTOP
frame #0: 0x00007fff8ad8fee2 libsystem_kernel.dylib`__psynch_mutexwait + 10
frame #1: 0x00007fff87f13a49
libsystem_pthread.dylib`_pthread_mutex_lock_wait + 89
frame #2: 0x00007fff849d1374 CoreFoundation`boundPairWrite + 52
frame #3: 0x00007fff848ed395 CoreFoundation`CFWriteStreamWrite + 437
* frame #4: 0x0000000103d5fe60 SymQual`-[SQSubmissionUpload
stream:handleEvent:](self=0x00007fe3f9e12a20, _cmd="stream:handleEvent:",
aStream=0x00007fe3f9d65f00, eventCode=4) + 2816 at SQSubmissionUpload.m:305
frame #5: 0x00007fff849529a4 CoreFoundation`_signalEventSync + 180
frame #6: 0x00007fff849528db CoreFoundation`_cfstream_solo_signalEventSync
+ 251
frame #7: 0x00007fff8495278c CoreFoundation`_CFStreamSignalEvent + 476
frame #8: 0x00007fff849d1572 CoreFoundation`boundPairWrite + 562
frame #9: 0x00007fff848ed395 CoreFoundation`CFWriteStreamWrite + 437
frame #10: 0x0000000103d5fe60 SymQual`-[SQSubmissionUpload
stream:handleEvent:](self=0x00007fe3f9e12a20, _cmd="stream:handleEvent:",
aStream=0x00007fe3f9d65f00, eventCode=4) + 2816 at SQSubmissionUpload.m:305
frame #11: 0x00007fff849529a4 CoreFoundation`_signalEventSync + 180
frame #12: 0x00007fff8499027e
CoreFoundation`_cfstream_shared_signalEventSync + 478
frame #13: 0x00007fff849125c1
CoreFoundation`__CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 17
frame #14: 0x00007fff8490441c CoreFoundation`__CFRunLoopDoSources0 + 556
frame #15: 0x00007fff8490393f CoreFoundation`__CFRunLoopRun + 927
frame #16: 0x00007fff84903338 CoreFoundation`CFRunLoopRunSpecific + 296
frame #17: 0x00007fff818d8e61 Foundation`-[NSRunLoop(NSRunLoop)
runMode:beforeDate:] + 270
frame #18: 0x00007fff8194aafd Foundation`-[NSRunLoop(NSRunLoop) run] + 74
frame #19: 0x0000000103c3ddec symquald`-[SQDaemon
run](self=0x00007fe3f9c03ae0, _cmd="run") + 2140 at SQDaemon.m:182
frame #20: 0x0000000103c38c02 symquald`main(argc=3,
argv=0x00007fff5bfc9978) + 482 at main.m:71
frame #21: 0x0000000103c37be4 symquald`start + 52
thread #3: tid = 0x82b0f1, 0x00007fff8ad8fee2
libsystem_kernel.dylib`__psynch_mutexwait + 10, name =
'com.apple.NSURLConnectionLoader'
frame #0: 0x00007fff8ad8fee2 libsystem_kernel.dylib`__psynch_mutexwait + 10
frame #1: 0x00007fff87f13a49
libsystem_pthread.dylib`_pthread_mutex_lock_wait + 89
frame #2: 0x00007fff849d0d57 CoreFoundation`boundPairRead + 151
frame #3: 0x00007fff849457a5 CoreFoundation`CFReadStreamRead + 389
frame #4: 0x00007fff817a9447 CFNetwork`spoolingRead(__CFReadStream*,
unsigned char*, long, CFStreamError*, unsigned char*, void*) + 165
frame #5: 0x00007fff849457a5 CoreFoundation`CFReadStreamRead + 389
frame #6: 0x00007fff81681442
CFNetwork`HTTPNetConnection::transmitRequest(HTTPNetStreamInfo*,
__CoreWriteStream*, CFStreamError*, unsigned char) + 1360
frame #7: 0x00007fff816ad5ed
CFNetwork`HTTPNetConnection::transmitRequest(void*) + 107
frame #8: 0x00007fff816851ca
CFNetwork`HTTPNetConnection::handleReadEventsDuringRequestBodyTransmission(void*,
unsigned long) + 802
frame #9: 0x00007fff81684b8e
CFNetwork`HTTPNetConnection::responseStreamCallback(void*, __CoreReadStream*,
unsigned long) + 90
frame #10: 0x00007fff81684ac9
CFNetwork`NetConnection::connectionResponse(__CoreReadStream*, unsigned long) +
87
frame #11: 0x00007fff81684a06
CFNetwork`CoreReadStreamClient::coreStreamEventsAvailable(unsigned long) + 60
frame #12: 0x00007fff81680c7d
CFNetwork`CoreStreamBase::_callClientNow(CoreStreamClient*) + 53
frame #13: 0x00007fff8167e5ff
CFNetwork`CoreStreamBase::_streamSetEventAndScheduleDelivery(unsigned long,
unsigned char) + 183
frame #14: 0x00007fff81682d41
CFNetwork`HTTPReadFilter::readHeaderBytes(StreamReader*, unsigned char,
unsigned char*, long, CFStreamError*) + 85
frame #15: 0x00007fff81682bbe
CFNetwork`HTTPReadFilter::canReadNoSignal(StreamReader*, CFStreamError*,
unsigned char) + 128
frame #16: 0x00007fff81683640
CFNetwork`HTTPReadFilter::_streamImpl_CanRead() + 126
frame #17: 0x00007fff81683a3d
CFNetwork`HTTPReadFilter::socketReadStreamCallback(unsigned long) + 179
frame #18: 0x00007fff8168397a
CFNetwork`HTTPReadFilter::_httpRdFilterStreamCallBack(__CFReadStream*, unsigned
long, void*) + 118
frame #19: 0x00007fff849529a4 CoreFoundation`_signalEventSync + 180
frame #20: 0x00007fff849528db CoreFoundation`_cfstream_solo_signalEventSync
+ 251
frame #21: 0x00007fff8495278c CoreFoundation`_CFStreamSignalEvent + 476
frame #22: 0x00007fff815cbea0
CFNetwork`SocketStream::dispatchSignalFromSocketCallbackUnlocked(SocketStreamSignalHolder*)
+ 58
frame #23: 0x00007fff815d11d6
CFNetwork`SocketStream::socketCallback(__CFSocket*, unsigned long, __CFData
const*, void const*) + 246
frame #24: 0x00007fff815d10a6
CFNetwork`SocketStream::_SocketCallBack_stream(__CFSocket*, unsigned long,
__CFData const*, void const*, void*) + 70
frame #25: 0x00007fff849521c4 CoreFoundation`__CFSocketPerformV0 + 996
frame #26: 0x00007fff849125c1
CoreFoundation`__CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 17
frame #27: 0x00007fff8490441c CoreFoundation`__CFRunLoopDoSources0 + 556
frame #28: 0x00007fff8490393f CoreFoundation`__CFRunLoopRun + 927
frame #29: 0x00007fff84903338 CoreFoundation`CFRunLoopRunSpecific + 296
frame #30: 0x00007fff815966e9 CFNetwork`+[NSURLConnection(Loader)
_resourceLoadLoop:] + 412
frame #31: 0x00007fff81a24c6f Foundation`__NSThread__start__ + 1351
frame #32: 0x00007fff87f10c13 libsystem_pthread.dylib`_pthread_body + 131
frame #33: 0x00007fff87f10b90 libsystem_pthread.dylib`_pthread_start + 168
frame #34: 0x00007fff87f0e375 libsystem_pthread.dylib`thread_start + 13 _______________________________________________
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