[xml] libxml and threads

[Massimo Cafaro <massimo cafaro unile it>]

Dear all,

sorry for asking about on the mailing list, but I did not find anything on the web site.
I have a multithreaded application in which each thread uses libxml2 for parsing in memory xml buffers etc.

Everything works fine, but I have found that many memory leaks are associated with libxml2 APIs. The leaks are small, but they are so many that this is a serious problem. Now, I strongly believe that it is entirely my fault, but I need to understand exactly how to use libxml2 in threaded applications.

Here is a sample memory leak:


Leak: 0x0110f690  size=48       string 'MUTX'
Call stack: [thread 280c000]: | 0x0 | _pthread_body | thread_starter | provider_thr | grelc_get_sql | xmlSAXParseMemoryWithData | xmlCreateMemoryParserCtxt | xmlNewParserCtxt | xmlInitParserCtxt | xmlDefaultSAXHandlerInit | __xmlDefaultSAXHandler | xmlGetGlobalState | xmlNewGlobalState | xmlInitializeGlobalState | xmlInitGlobals | xmlNewMutex | malloc | malloc_zone_malloc 

It looks like a mutex object is never deallocated.

The code looks like

xmlDocPtr doc;
...

doc = xmlParseMemory (docname, strlen(docname) - 1);
...
xmlCleanupParser();


Is this the way to write this kind of code? I was not able to find any example of threaded code. I have found some APIs for dealing with threads tough.
Placing a xmlLockLibrary() and xmlUnlockLibrary() before and after to model a critical section does not help (the same holds if I create a mutex object and call related lock/unlock functions). The libxml2 I am using is the latest one officially released on January. I am working on Mac oS X 10.3.8

Thanks in advance,
Massimo


-- 

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Massimo Cafaro, Ph.D.        Center for Advanced Computational Technologies
Assistant Professor               Voice  +39 0832 297371    
University of Lecce, Italy      Fax    +39 0832 297279     
Faculty of Engineering         E-mail massimo cafaro unile it            
Via per Monteroni                              cafaro cacr caltech edu
73100 Lecce, Italy                Web     http://sara.unile.it/~cafaro

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