Re: [xml] libxml and threads

[Daniel Veillard <veillard redhat com>]

On Wed, Feb 23, 2005 at 11:55:41AM +0100, Massimo Cafaro wrote:
> On Feb 23, 2005, at 11:38 AM, Daniel Veillard wrote: 
> > > 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   
> >  
> >   The threads code is the only one which can legally do direct 
> > malloc() 
> > without using xmlMalloc(), so it's among the memory use I won't 
> > detect 
> > leaks in regression tests. 
>  
> I do not understand this. What is exactly what you call threads code? 

   code from libxml2 thread.c module.

> The leaks originates in the xmlParseMemory() function, which is called 

   No. The leak originate when the application wide thread mutex is
 allocated. The fact it comes from xmlParseMemory() is just that you did
not initialize the libxml2 module as explained 
    1/ in the docs
       http://xmlsoft.org/threads.html
       "call xmlInitParser() in the "main" thread before using any of the
        libxml2 API (except possibly selecting a different memory allocator)"
       obviously you are not doing this otherwise that mutex would
       have been allocated by the time you call xmlParseMemory()
    2/ in my previous mail

> in my application many times in many threads. I do not know exactly how 
> do you check for leaks, I am using a standard tool on Mac OS X. May be 
> it is worth saying here that the leaks are exactly the same on linux, 
> as detected by valgrind. 

  Then your code is likely in error, very first thing is to follow the
documentation about thread safety ! Then come back with a complete
example reproducing the problem on Linux, not 3 lines out of context.

Daniel



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