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<p class="MsoNormal"><span lang="ES-TRAD" style="font-size:11.0pt;font-family:"Calibri",sans-serif">Sure Andrew,
<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="ES-TRAD" style="font-size:11.0pt;font-family:"Calibri",sans-serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif">Here it is the call stack from Visual Studio for both threads (I just copied the top calls where GDAL is involved, just for easy reading. If you need the whole stack just let
me know):<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif">THREAD 1:<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"> ntdll.dll!_NtWaitForSingleObject@12‑() Unknown<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"> ntdll.dll!_RtlpWaitOnCriticalSection@8‑() Unknown<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"> ntdll.dll!_RtlEnterCriticalSection@4‑() Unknown<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"> gdal201.dll!CPLAcquireMutex(_CPLMutex * hMutexIn, double dfWaitInSeconds) Line 806 C++<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"> gdal201.dll!GDALDataset::EnterReadWrite(GDALRWFlag eRWFlag) Line 6102 C++<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"> gdal201.dll!GDALRasterBand::EnterReadWrite(GDALRWFlag eRWFlag) Line 5290 C++<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"> gdal201.dll!GDALRasterBlock::Write() Line 742 C++<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"> gdal201.dll!GDALRasterBlock::Internalize() Line 917 C++<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"> gdal201.dll!GDALRasterBand::GetLockedBlockRef(int nXBlockOff, int nYBlockOff, int bJustInitialize) Line 1126 C++<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif">> Test.exe!RasterBandPixelAccess::SetValueAtPixel<short>(const int & pX, const int & pY, const short & value) Line 180 C++<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif">THREAD 2:<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"> ntdll.dll!_NtWaitForSingleObject@12‑() Unknown<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"> KernelBase.dll!_WaitForSingleObjectEx@12‑() Unknown<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"> kernel32.dll!_WaitForSingleObjectExImplementation@12‑() Unknown<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"> kernel32.dll!_WaitForSingleObject@8‑() Unknown<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"> gdal201.dll!CPLCondWait(_CPLCond * hCond, _CPLMutex * hClientMutex) Line 937 C++<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"> gdal201.dll!GDALAbstractBandBlockCache::WaitKeepAliveCounter() Line 134 C++<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"> gdal201.dll!GDALArrayBandBlockCache::FlushCache() Line 312 C++<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"> gdal201.dll!GDALRasterBand::FlushCache() Line 865 C++<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"> gdal201.dll!GDALDataset::FlushCache() Line 386 C++<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"> gdal201.dll!GDALPamDataset::FlushCache() Line 159 C++<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"> gdal201.dll!GTiffDataset::Finalize() Line 6180 C++<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"> gdal201.dll!GTiffDataset::~GTiffDataset() Line 6135 C++<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"> gdal201.dll!GTiffDataset::`scalar deleting destructor'(unsigned int) C++<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"> gdal201.dll!GDALClose(void * hDS) Line 2998 C++<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif">> Test.exe!main::__l2::<lambda>(std::basic_string<char,std::char_traits<char>,std::allocator<char> > sourcefilePath, std::basic_string<char,std::char_traits<char>,std::allocator<char>
> targetFilePath, int threadID) Line 66 C++<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif">From:</span></b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"> Andrew Bell [mailto:andrew.bell.ia@gmail.com]
<br>
<b>Sent:</b> 26 September, 2016 16:06<br>
<b>To:</b> Francisco Javier Calzado <francisco.javier.calzado@ericsson.com><br>
<b>Cc:</b> gdal-dev@lists.osgeo.org<br>
<b>Subject:</b> Re: [gdal-dev] Multithread deadlock<o:p></o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
<div>
<p class="MsoNormal">Deadlocks are usually easy to debug if you can get a traceback when deadlocked. If you can attach with gdb (or run in the debugger) and reproduce and post the stack at the time ('where' from gdb), it should be no problem to fix. Trying
to reproduce on different hardware can be difficult.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">On Mon, Sep 26, 2016 at 9:33 AM, Francisco Javier Calzado <<a href="mailto:francisco.javier.calzado@ericsson.com" target="_blank">francisco.javier.calzado@ericsson.com</a>> wrote:<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Hi guys,<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">I am experiencing a deadlock with just 2 threads in a single reader & multiple writer scenario. This is, threads read from the same input file (using different handlers) and then
write different output files. Deadlock comes when the block cache gets filled. The situation is the following:<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
<p>-<span style="font-size:7.0pt"> </span>T1 and T2 read datasets D1 and D2, both pointing to the same input raster (GTiff).<o:p></o:p></p>
<p>-<span style="font-size:7.0pt"> </span>Block cache gets filled.<o:p></o:p></p>
<p>-<span style="font-size:7.0pt"> </span>T1 tries to lock one block in the cache to write data. But cache is full, so it tries to free dirty blocks from T2 (as seen in Internalize() method). For that purpose, it requires apparently a mutex from D2.<o:p></o:p></p>
<p>-<span style="font-size:7.0pt"> </span>However T2 is in a state where must wait for thread T1 to finish working with T2’s blocks. In this state, T2 has a mutex acquired from D2.
<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">At least, that is what it seems to be happening based on source code. Maybe I’m wrong, I don’t have a full picture overview about how GDAL is internally working. The thing is that
I can reproduce this issue with the following test code and dataset:<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><a href="https://drive.google.com/file/d/0B-OCl1FjBi0YSkU3RUozZjc5SnM/view?usp=sharing" target="_blank">https://drive.google.com/file/d/0B-OCl1FjBi0YSkU3RUozZjc5SnM/view?usp=sharing</a><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Oddly enough, ticket with number #6163 is supposed to fix this, but its failing in my case. I am working with GDAL 2.1.0 version under VS2015 (x32, Debug) compilation.
<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Even, what do you think?<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="ES-TRAD"> </span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="ES-TRAD">Thanks!</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="ES-TRAD">Javier C.</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
</div>
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<p class="MsoNormal"><br>
_______________________________________________<br>
gdal-dev mailing list<br>
<a href="mailto:gdal-dev@lists.osgeo.org">gdal-dev@lists.osgeo.org</a><br>
<a href="http://lists.osgeo.org/mailman/listinfo/gdal-dev" target="_blank">http://lists.osgeo.org/mailman/listinfo/gdal-dev</a><o:p></o:p></p>
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<p class="MsoNormal"><br>
<br clear="all">
<o:p></o:p></p>
<div>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
<p class="MsoNormal">-- <o:p></o:p></p>
<div>
<p class="MsoNormal">Andrew Bell<br>
<a href="mailto:andrew.bell.ia@gmail.com" target="_blank">andrew.bell.ia@gmail.com</a><o:p></o:p></p>
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