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<p>If your program uses threads, and you don't make sure to wait for
their termination before calling GDALDestroy, this could explain
memory corruption if they use GDAL TLS, while GDALDestroy() is
cleaning the TLS structures. I'll stop random guessing here.</p>
<p>And you can just get rid of the GDALDestroy() call if it is an
annoyance. It just frees memory, which process termination does
anyway. It is just there so that no still-reachable memory is
reported when running under Valgrind or other similar analyzers.</p>
<div class="moz-cite-prefix">Le 19/09/2024 à 03:51, Fox, Shawn D
(US) via gdal-dev a écrit :<br>
</div>
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<p class="MsoNormal">Just for fun, I changed by code back to
cause the crash again. Now it’s difficult to reproduce but
here is the part of the callstack showing where the issue
occurs. The CPLCleanupTLSList function is the function of
interest as it loops over some type of list. Within a
conditional it is adding two numbers together in an array
offset and testing a pointer to determine whether to free some
memory. This is far down into the weeds of GDAL so I’ve no
idea what this function is doing but it’s above my level of
understanding of GDAL internals. We don’t attempt to use any
networking capabilities within GDAL as far as I know. When I
get it to crash again I’ll step into it some more to see if
something jumps out at me.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">#0 0x00007fc79b81e241 in unlink_chunk.isra
() from /lib64/libc.so.6<o:p></o:p></p>
<p class="MsoNormal">#1 0x00007fc79b81e465 in
malloc_consolidate () from /lib64/libc.so.6<o:p></o:p></p>
<p class="MsoNormal">#2 0x00007fc79b81fae0 in _int_free () from
/lib64/libc.so.6<o:p></o:p></p>
<p class="MsoNormal">#3 0x00007fc792ab9708 in VSIFree
(pData=0x9bfd40) at cpl_vsisimple.cpp:873<o:p></o:p></p>
<p class="MsoNormal">#4 0x00007fc792a78820 in CPLCleanupTLSList
(papTLSList=0x7ab950) at cpl_multiproc.cpp:467<o:p></o:p></p>
<p class="MsoNormal">#5 0x00007fc792a799ec in CPLCleanupTLS ()
at cpl_multiproc.cpp:2247<o:p></o:p></p>
<p class="MsoNormal">#6 0x00007fc79252667c in
GDALDriverManager::~GDALDriverManager (this=0x848ae0,
__in_chrg=<optimized out>) at gdaldrivermanager.cpp:274<o:p></o:p></p>
<p class="MsoNormal">#7 0x00007fc792526746 in
GDALDriverManager::~GDALDriverManager (this=0x848ae0,
__in_chrg=<optimized out>) at gdaldrivermanager.cpp:335<o:p></o:p></p>
<p class="MsoNormal">#8 0x00007fc792527989 in
GDALDestroyDriverManager () at gdaldrivermanager.cpp:915<o:p></o:p></p>
<p class="MsoNormal">#9 0x00007fc792520fce in GDALDestroy () at
gdaldllmain.cpp:86<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal" style="text-autospace:none"><span
style="font-size:10.0pt;font-family:"Tahoma",sans-serif;color:black">Shawn
Fox</span><o:p></o:p></p>
<div
style="border:none;border-top:solid #E1E1E1 1.0pt;padding:3.0pt 0in 0in 0in">
<p class="MsoNormal"><b>From:</b> Andrew Bell
<a class="moz-txt-link-rfc2396E" href="mailto:andrew.bell.ia@gmail.com"><andrew.bell.ia@gmail.com></a> <br>
<b>Sent:</b> Wednesday, September 18, 2024 5:50 PM<br>
<b>To:</b> Fox, Shawn D (US) <a class="moz-txt-link-rfc2396E" href="mailto:shawn.fox@baesystems.us"><shawn.fox@baesystems.us></a><br>
<b>Cc:</b> <a class="moz-txt-link-abbreviated" href="mailto:gdal-dev@lists.osgeo.org">gdal-dev@lists.osgeo.org</a><br>
<b>Subject:</b> Re: [gdal-dev] Call to GDALDestroy results
in occasional core dump, GDAL 3.4.2<o:p></o:p></p>
</div>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
<div>
<div>
<p class="MsoNormal">On Wed, Sep 18, 2024 at 8:32 PM
Fox, Shawn D (US) via gdal-dev <<a
href="mailto:gdal-dev@lists.osgeo.org"
moz-do-not-send="true" class="moz-txt-link-freetext">gdal-dev@lists.osgeo.org</a>>
wrote:<o:p></o:p></p>
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<div>
<p class="MsoNormal"
style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">In our case
we have a singleton class that acts as a façade
and all of our calls to GDAL Apis are done by
the methods of this class. The rest of our code
base only interacts with the singleton so that
we only have one project that actually depends
directly on the GDAL library. Since the
_instance member is a static smart pointer the
destructor of our class and the GDALDestroy
function is being called after the main function
exits.<o:p></o:p></p>
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<div>
<p class="MsoNormal"><o:p> </o:p></p>
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<div>
<p class="MsoNormal">This is not a great plan unless you
understand exactly the order of things being
destroyed, which is not well-defined between
compilation units unless you have done things
to guarantee it. It seems likely that GDALDestroy() is
attempting to free things already destroyed during
program tear-down. Since your program is exiting, I
can't imagine you need to call GDALDestroy() at all.
You could also eliminate this issue by instantiating
your GDAL class-thingee as the first line of your
program rather than as a static.<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
</div>
<p class="MsoNormal"><span class="gmailsignatureprefix">-- </span><o:p></o:p></p>
<div>
<p class="MsoNormal">Andrew Bell<br>
<a href="mailto:andrew.bell.ia@gmail.com"
target="_blank" moz-do-not-send="true"
class="moz-txt-link-freetext">andrew.bell.ia@gmail.com</a><o:p></o:p></p>
</div>
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<pre class="moz-signature" cols="72">--
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My software is free, but my time generally not.</pre>
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