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diff --git a/doc/xmlmem.html b/doc/xmlmem.html index a979f7d..ba9e517 100644 --- a/doc/xmlmem.html +++ b/doc/xmlmem.html @@ -7,21 +7,24 @@ H1 {font-family: Verdana,Arial,Helvetica} H2 {font-family: Verdana,Arial,Helvetica} H3 {font-family: Verdana,Arial,Helvetica} A:link, A:visited, A:active { text-decoration: underline } -</style><title>Memory Management</title></head><body bgcolor="#8b7765" text="#000000" link="#a06060" vlink="#000000"><table border="0" width="100%" cellpadding="5" cellspacing="0" align="center"><tr><td width="120"><a href="http://swpat.ffii.org/"><img src="epatents.png" alt="Action against software patents" /></a></td><td width="180"><a href="http://www.gnome.org/"><img src="gnome2.png" alt="Gnome2 Logo" /></a><a href="http://www.w3.org/Status"><img src="w3c.png" alt="W3C Logo" /></a><a href="http://www.redhat.com/"><img src="redhat.gif" alt="Red Hat Logo" /></a><div align="left"><a href="http://xmlsoft.org/"><img src="Libxml2-Logo-180x168.gif" alt="Made with Libxml2 Logo" /></a></div></td><td><table border="0" width="90%" cellpadding="2" cellspacing="0" align="center" bgcolor="#000000"><tr><td><table width="100%" border="0" cellspacing="1" cellpadding="3" bgcolor="#fffacd"><tr><td align="center"><h1>The XML C parser and toolkit of Gnome</h1><h2>Memory Management</h2></td></tr></table></td></tr></table></td></tr></table><table border="0" cellpadding="4" cellspacing="0" width="100%" align="center"><tr><td bgcolor="#8b7765"><table border="0" cellspacing="0" cellpadding="2" width="100%"><tr><td valign="top" width="200" bgcolor="#8b7765"><table border="0" cellspacing="0" cellpadding="1" width="100%" bgcolor="#000000"><tr><td><table width="100%" border="0" cellspacing="1" cellpadding="3"><tr><td colspan="1" bgcolor="#eecfa1" align="center"><center><b>Developer Menu</b></center></td></tr><tr><td bgcolor="#fffacd"><form action="search.php" enctype="application/x-www-form-urlencoded" method="get"><input name="query" type="text" size="20" value="" /><input name="submit" type="submit" value="Search ..." /></form><ul><li><a href="index.html" style="font-weight:bold">Main Menu</a></li><li><a href="html/index.html" style="font-weight:bold">Reference Manual</a></li><li><a href="examples/index.html" style="font-weight:bold">Code Examples</a></li><li><a href="guidelines.html">XML Guidelines</a></li><li><a href="tutorial/index.html">Tutorial</a></li><li><a href="xmlreader.html">The Reader Interface</a></li><li><a href="ChangeLog.html">ChangeLog</a></li><li><a href="XSLT.html">XSLT</a></li><li><a href="python.html">Python and bindings</a></li><li><a href="architecture.html">libxml2 architecture</a></li><li><a href="tree.html">The tree output</a></li><li><a href="interface.html">The SAX interface</a></li><li><a href="xmlmem.html">Memory Management</a></li><li><a href="xmlio.html">I/O Interfaces</a></li><li><a href="library.html">The parser interfaces</a></li><li><a href="entities.html">Entities or no entities</a></li><li><a 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bgcolor="#fffacd"><ul><li><a href="http://mail.gnome.org/archives/xml/">Mail archive</a></li><li><a href="http://xmlsoft.org/XSLT/">XSLT libxslt</a></li><li><a href="http://phd.cs.unibo.it/gdome2/">DOM gdome2</a></li><li><a href="http://www.aleksey.com/xmlsec/">XML-DSig xmlsec</a></li><li><a href="ftp://xmlsoft.org/">FTP</a></li><li><a href="http://www.zlatkovic.com/projects/libxml/">Windows binaries</a></li><li><a href="http://opencsw.org/packages/libxml2">Solaris binaries</a></li><li><a href="http://www.explain.com.au/oss/libxml2xslt.html">MacOsX binaries</a></li><li><a href="http://lxml.de/">lxml Python bindings</a></li><li><a href="http://cpan.uwinnipeg.ca/dist/XML-LibXML">Perl bindings</a></li><li><a href="http://libxmlplusplus.sourceforge.net/">C++ bindings</a></li><li><a href="http://www.zend.com/php5/articles/php5-xmlphp.php#Heading4">PHP bindings</a></li><li><a href="http://sourceforge.net/projects/libxml2-pas/">Pascal bindings</a></li><li><a href="http://libxml.rubyforge.org/">Ruby bindings</a></li><li><a href="http://tclxml.sourceforge.net/">Tcl bindings</a></li><li><a href="http://bugzilla.gnome.org/buglist.cgi?product=libxml2">Bug Tracker</a></li></ul></td></tr></table></td></tr></table></td><td valign="top" bgcolor="#8b7765"><table border="0" cellspacing="0" cellpadding="1" width="100%"><tr><td><table border="0" cellspacing="0" cellpadding="1" width="100%" bgcolor="#000000"><tr><td><table border="0" cellpadding="3" cellspacing="1" width="100%"><tr><td bgcolor="#fffacd"><p>Table of Content:</p><ol><li><a href="#General3">General overview</a></li> +</style><title>Memory Management</title></head><body bgcolor="#8b7765" text="#000000" link="#a06060" vlink="#000000"><table border="0" width="100%" cellpadding="5" cellspacing="0" align="center"><tr><td width="120"><a href="http://swpat.ffii.org/"><img src="epatents.png" alt="Action against software patents" /></a></td><td width="180"><a href="http://www.gnome.org/"><img src="gnome2.png" alt="Gnome2 Logo" /></a><a href="http://www.w3.org/Status"><img src="w3c.png" alt="W3C Logo" /></a><a href="http://www.redhat.com/"><img src="redhat.gif" alt="Red Hat Logo" /></a><div align="left"><a href="http://xmlsoft.org/"><img src="Libxml2-Logo-180x168.gif" alt="Made with Libxml2 Logo" /></a></div></td><td><table border="0" width="90%" cellpadding="2" cellspacing="0" align="center" bgcolor="#000000"><tr><td><table width="100%" border="0" cellspacing="1" cellpadding="3" bgcolor="#fffacd"><tr><td align="center"><h1>The XML C parser and toolkit of Gnome</h1><h2>Memory Management</h2></td></tr></table></td></tr></table></td></tr></table><table border="0" cellpadding="4" cellspacing="0" width="100%" align="center"><tr><td bgcolor="#8b7765"><table border="0" cellspacing="0" cellpadding="2" width="100%"><tr><td valign="top" width="200" bgcolor="#8b7765"><table border="0" cellspacing="0" cellpadding="1" width="100%" bgcolor="#000000"><tr><td><table width="100%" border="0" cellspacing="1" cellpadding="3"><tr><td colspan="1" bgcolor="#eecfa1" align="center"><center><b>Developer Menu</b></center></td></tr><tr><td bgcolor="#fffacd"><form action="search.php" enctype="application/x-www-form-urlencoded" method="get"><input name="query" type="text" size="20" value="" /><input name="submit" type="submit" value="Search ..." /></form><ul><li><a href="index.html" style="font-weight:bold">Main Menu</a></li><li><a href="html/index.html" style="font-weight:bold">Reference Manual</a></li><li><a href="examples/index.html" style="font-weight:bold">Code Examples</a></li><li><a href="guidelines.html">XML Guidelines</a></li><li><a href="tutorial/index.html">Tutorial</a></li><li><a href="xmlreader.html">The Reader Interface</a></li><li><a href="ChangeLog.html">ChangeLog</a></li><li><a href="XSLT.html">XSLT</a></li><li><a href="python.html">Python and bindings</a></li><li><a href="architecture.html">libxml2 architecture</a></li><li><a href="tree.html">The tree output</a></li><li><a href="interface.html">The SAX interface</a></li><li><a href="xmlmem.html">Memory Management</a></li><li><a href="xmlio.html">I/O Interfaces</a></li><li><a href="library.html">The parser interfaces</a></li><li><a href="entities.html">Entities or no entities</a></li><li><a href="namespaces.html">Namespaces</a></li><li><a href="upgrade.html">Upgrading 1.x code</a></li><li><a href="threads.html">Thread safety</a></li><li><a href="DOM.html">DOM Principles</a></li><li><a href="example.html">A real example</a></li><li><a href="xml.html">flat page</a>, <a href="site.xsl">stylesheet</a></li></ul></td></tr></table><table width="100%" border="0" cellspacing="1" cellpadding="3"><tr><td colspan="1" bgcolor="#eecfa1" align="center"><center><b>API Indexes</b></center></td></tr><tr><td bgcolor="#fffacd"><ul><li><a href="APIchunk0.html">Alphabetic</a></li><li><a href="APIconstructors.html">Constructors</a></li><li><a href="APIfunctions.html">Functions/Types</a></li><li><a href="APIfiles.html">Modules</a></li><li><a href="APIsymbols.html">Symbols</a></li></ul></td></tr></table><table width="100%" border="0" cellspacing="1" cellpadding="3"><tr><td colspan="1" bgcolor="#eecfa1" align="center"><center><b>Related links</b></center></td></tr><tr><td bgcolor="#fffacd"><ul><li><a href="http://mail.gnome.org/archives/xml/">Mail archive</a></li><li><a href="http://xmlsoft.org/XSLT/">XSLT libxslt</a></li><li><a href="http://phd.cs.unibo.it/gdome2/">DOM gdome2</a></li><li><a href="http://www.aleksey.com/xmlsec/">XML-DSig xmlsec</a></li><li><a href="ftp://xmlsoft.org/">FTP</a></li><li><a href="http://www.zlatkovic.com/projects/libxml/">Windows binaries</a></li><li><a href="http://opencsw.org/packages/libxml2">Solaris binaries</a></li><li><a href="http://www.explain.com.au/oss/libxml2xslt.html">MacOsX binaries</a></li><li><a href="http://lxml.de/">lxml Python bindings</a></li><li><a href="http://cpan.uwinnipeg.ca/dist/XML-LibXML">Perl bindings</a></li><li><a href="http://libxmlplusplus.sourceforge.net/">C++ bindings</a></li><li><a href="http://www.zend.com/php5/articles/php5-xmlphp.php#Heading4">PHP bindings</a></li><li><a href="http://sourceforge.net/projects/libxml2-pas/">Pascal bindings</a></li><li><a href="http://libxml.rubyforge.org/">Ruby bindings</a></li><li><a href="http://tclxml.sourceforge.net/">Tcl bindings</a></li><li><a href="http://bugzilla.gnome.org/buglist.cgi?product=libxml2">Bug Tracker</a></li></ul></td></tr></table></td></tr></table></td><td valign="top" bgcolor="#8b7765"><table border="0" cellspacing="0" cellpadding="1" width="100%"><tr><td><table border="0" cellspacing="0" cellpadding="1" width="100%" bgcolor="#000000"><tr><td><table border="0" cellpadding="3" cellspacing="1" width="100%"><tr><td bgcolor="#fffacd"><p>Table of Content:</p><ol> + <li><a href="#General3">General overview</a></li> <li><a href="#setting">Setting libxml2 set of memory routines</a></li> <li><a href="#cleanup">Cleaning up after using the library</a></li> <li><a href="#Debugging">Debugging routines</a></li> <li><a href="#General4">General memory requirements</a></li> <li><a href="#Compacting">Returning memory to the kernel</a></li> </ol><h3><a name="General3" id="General3">General overview</a></h3><p>The module <code><a href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlmemory.h</a></code> -provides the interfaces to the libxml2 memory system:</p><ul><li>libxml2 does not use the libc memory allocator directly but xmlFree(), +provides the interfaces to the libxml2 memory system:</p><ul> + <li>libxml2 does not use the libc memory allocator directly but xmlFree(), xmlMalloc() and xmlRealloc()</li> <li>those routines can be reallocated to a specific set of routine, by default the libc ones i.e. free(), malloc() and realloc()</li> <li>the xmlmemory.c module includes a set of debugging routine</li> </ul><h3><a name="setting" id="setting">Setting libxml2 set of memory routines</a></h3><p>It is sometimes useful to not use the default memory allocator, either for debugging, analysis or to implement a specific behaviour on memory management -(like on embedded systems). Two function calls are available to do so:</p><ul><li><a href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlMemGet +(like on embedded systems). Two function calls are available to do so:</p><ul> + <li><a href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlMemGet ()</a> which return the current set of functions in use by the parser</li> <li><a href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlMemSetup()</a> which allow to set up a new set of memory allocation functions</li> @@ -31,7 +34,8 @@ compatibles).</p><h3><a name="cleanup" id="cleanup">Cleaning up after using the allocation before the parser is fully functional (some encoding structures for example). This also mean that once parsing is finished there is a tiny amount of memory (a few hundred bytes) which can be recollected if you don't -reuse the library or any document built with it:</p><ul><li><a href="http://xmlsoft.org/html/libxml-parser.html">xmlCleanupParser +reuse the library or any document built with it:</p><ul> + <li><a href="http://xmlsoft.org/html/libxml-parser.html">xmlCleanupParser ()</a> is a centralized routine to free the library state and data. Note that it won't deallocate any produced tree if any (use the xmlFreeDoc() and related routines for this). This should be called only when the library @@ -47,7 +51,8 @@ of the consequences in multithreaded applications.</p><h3><a name="Debugging" id a set of memory allocation debugging routines keeping track of all allocated blocks and the location in the code where the routine was called. A couple of other debugging routines allow to dump the memory allocated infos to a file -or call a specific routine when a given block number is allocated:</p><ul><li><a href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlMallocLoc()</a> +or call a specific routine when a given block number is allocated:</p><ul> + <li><a href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlMallocLoc()</a> <a href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlReallocLoc()</a> and <a href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlMemStrdupLoc()</a> are the memory debugging replacement allocation routines</li> @@ -63,7 +68,8 @@ resulting in major portability problems!).</p><p>If the .memdump reports a leak, also tries to give some information about the content and structure of the allocated blocks left. This is sufficient in most cases to find the culprit, but not always. Assuming the allocation problem is reproducible, it is -possible to find more easily:</p><ol><li>write down the block number xxxx not allocated</li> +possible to find more easily:</p><ol> + <li>write down the block number xxxx not allocated</li> <li>export the environment variable XML_MEM_BREAKPOINT=xxxx , the easiest when using GDB is to simply give the command <p><code>set environment XML_MEM_BREAKPOINT xxxx</code></p> @@ -81,7 +87,8 @@ used and proved extremely efficient until now. Lately I have also used <a href=" success, it is tied to the i386 architecture since it works by emulating the processor and instruction set, it is slow but extremely efficient, i.e. it spot memory usage errors in a very precise way.</p><h3><a name="General4" id="General4">General memory requirements</a></h3><p>How much libxml2 memory require ? It's hard to tell in average it depends -of a number of things:</p><ul><li>the parser itself should work in a fixed amount of memory, except for +of a number of things:</p><ul> + <li>the parser itself should work in a fixed amount of memory, except for information maintained about the stacks of names and entities locations. The I/O and encoding handlers will probably account for a few KBytes. This is true for both the XML and HTML parser (though the HTML parser |