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POdid I find a libxml2 bug (memory leak in multi-threaded parsing)?
 

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  1. POdid I find a libxml2 bug (memory leak in multi-threaded parsing)?
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    <p>I am working actually on a data processing code using <a href="http://xmlsoft.org/" rel="noreferrer">libxml2</a>. I am stuck on a memory leak impossible to remove . Here is a minimal code to generate it :</p> <pre><code>#include &lt;stdlib.h&gt; #include &lt;stdio.h&gt; #include &lt;libxml/parser.h&gt; #include &lt;libxml/tree.h&gt; #include &lt;omp.h&gt; int main(void) { xmlDoc *doc; int tn; char fname[32]; omp_set_num_threads(2); xmlInitParser(); #pragma omp parallel private(doc,tn,fname) { tn = omp_get_thread_num(); sprintf(fname,"testdoc%d.xml",tn); doc = xmlReadFile(fname,NULL,0); printf("document %s parsed on thread %d (%p)\n",fname,tn,doc); xmlFreeDoc(doc); } xmlCleanupParser(); return EXIT_SUCCESS; } </code></pre> <p>At runtime, output is :</p> <pre><code>document testdoc0.xml parsed on thread 0 (0x1005413a0) document testdoc1.xml parsed on thread 1 (0x1005543c0) </code></pre> <p>confirming that we really have multi-threading and that <code>doc</code> is really private in the parallel region. One can notice that I applied correctly the thread safety instructions for using libxml2 (<a href="http://xmlsoft.org/threads.html" rel="noreferrer">http://xmlsoft.org/threads.html</a>). Valgrind reports :</p> <pre><code>HEAP SUMMARY: in use at exit: 9,000 bytes in 8 blocks total heap usage: 956 allocs, 948 frees, 184,464 bytes allocated 968 bytes in 1 blocks are definitely lost in loss record 6 of 8 at 0x1000107AF: malloc (vg_replace_malloc.c:236) by 0x1000B2590: xmlGetGlobalState (in /opt/local/lib/libxml2.2.dylib) by 0x1000B1A18: __xmlDefaultSAXHandler (in /opt/local/lib/libxml2.2.dylib) by 0x100106D18: xmlDefaultSAXHandlerInit (in /opt/local/lib/libxml2.2.dylib) by 0x100041BE7: xmlInitParserCtxt (in /opt/local/lib/libxml2.2.dylib) by 0x100042145: xmlNewParserCtxt (in /opt/local/lib/libxml2.2.dylib) by 0x10004615E: xmlCreateURLParserCtxt (in /opt/local/lib/libxml2.2.dylib) by 0x10005B56B: xmlReadFile (in /opt/local/lib/libxml2.2.dylib) by 0x100000E03: main.omp_fn.0 (in ./xtest) by 0x100028FA3: gomp_thread_start (in /opt/local/lib/gcc44/libgomp.1.dylib) by 0x1001E8535: _pthread_start (in /usr/lib/libSystem.B.dylib) by 0x1001E83E8: thread_start (in /usr/lib/libSystem.B.dylib) LEAK SUMMARY: definitely lost: 968 bytes in 1 blocks indirectly lost: 0 bytes in 0 blocks possibly lost: 0 bytes in 0 blocks still reachable: 8,032 bytes in 7 blocks suppressed: 0 bytes in 0 blocks Reachable blocks (those to which a pointer was found) are not shown. To see them, rerun with: --leak-check=full --show-reachable=yes </code></pre> <p>This is working for me whatever the XML document used. I am using libxml 2.7.8, on Mac OS X 10.6.5 with gcc 4.4.5.</p> <p>Is someone able to reproduce this bug ?</p> <p>Thanks,</p> <p>Antonin</p>
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    1. USDervin Thunk
    1. USAntonin Portelli
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      1. POdid I find a libxml2 bug (memory leak in multi-threaded parsing)?
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      1. VTUpMod
    2. VO
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      1. POdid I find a libxml2 bug (memory leak in multi-threaded parsing)?
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      1. POdid I find a libxml2 bug (memory leak in multi-threaded parsing)?
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    1. COI don't see any what that code could generate that output. Maybe you trimmed the code too much.
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      1. POdid I find a libxml2 bug (memory leak in multi-threaded parsing)?
      1. USHans Passant
    2. COIs the size of the leak dependant on which XML file you parse?
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      1. POdid I find a libxml2 bug (memory leak in multi-threaded parsing)?
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    3. CO@Hans Passant : I don't see neither why this code is doing that, but it is, in a clean environment. I want to know if other people are able to reproduce that before reporting a bug.
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      1. POdid I find a libxml2 bug (memory leak in multi-threaded parsing)?
      1. USAntonin Portelli
 

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