Re: Concurrent tasks are getting hung up
Re: Concurrent tasks are getting hung up
- Subject: Re: Concurrent tasks are getting hung up
- From: Greg Parker <email@hidden>
- Date: Thu, 09 Oct 2014 22:32:26 -0700
On Oct 9, 2014, at 8:58 PM, Steve Mills <email@hidden> wrote:
>
> On Oct 9, 2014, at 17:25:05, Greg Parker <email@hidden> wrote:
>>
>> This thread is stopped inside dispatch_once(), presumably waiting for some other thread to perform the once operation.
>>
>> Assuming dispatch_once is working normally, there should be one thread inside readMakerNoteProps() and dispatch_once_f() that is doing something else. Can you find it? What is it doing?
>
> Found a thread that looks different:
>
> #0 0x00007fff8d46ca56 in semaphore_wait_trap ()
> #1 0x00007fff97c879f9 in _dispatch_semaphore_wait_slow ()
> #2 0x00007fff95f087ef in xpc_connection_send_message_with_reply_sync ()
> #3 0x00007fff925acbde in _LSCopyApplicationInformation ()
> #4 0x00007fff95898450 in ProcessInformationCopyDictionary ()
> #5 0x00007fff90efca3e in ___lldb_unnamed_function3$$MetadataLib.dylib ()
> #6 0x00007fff97c8328d in _dispatch_client_callout ()
> #7 0x00007fff97c831fc in dispatch_once_f ()
> #8 0x00007fff90efc50f in readMakerNoteProps ()
> #9 0x00007fff8bd982f9 in readMakerNoteProps ()
> #10 0x00007fff8bd4834d in metadataFromDatablock ()
> #11 0x00007fff8bd47bf8 in metadataFromDatablock ()
> #12 0x00007fff8bd7afed in createMetadataFromDatabuffer ()
> #13 0x00007fff8bd7194e in readExifData ()
> #14 0x00007fff8bd705ff in initImageJPEG ()
> #15 0x00007fff8bd6f1d6 in _CGImagePluginInitJPEG ()
> #16 0x00007fff8bd4528c in makeImagePlus ()
> #17 0x00007fff8bd6a469 in CGImageSourceCreateImageAtIndex ()
> #18 0x00000001000052a0 in -[FFGraphicSearch doesImageMatchURL:] at /Users/tut/Dropbox/FotoFind/FotoFind/FFGraphicSearch.mm:161
That looks like LaunchServices waiting for an XPC reply from something, probably launchservicesd. You should try sampling launchservicesd while this is hanging to see if the server is getting stuck while processing the request.
Odds are that it's a bug in LaunchServices client or server and not your code, though, unless you have a memory smasher or file descriptor error that is breaking LaunchServices' XPC connection. I'd recommend filing a bug report with instructions to make your project hang plus a sysdiagnose captured during the hang (which will sample both your app and launchservicesd).
--
Greg Parker email@hidden Runtime Wrangler
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