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Re: [xml] Help: memory leak ??

The first thing which you must do when you encounter a problem with your
code is to *very carefully* debug your logic.  It is really not fair to
expect the libxml2 developers and other list members to do this for you. 
When this problem was first sent in, the obvious error in not freeing the
return value from xmlGetProp was kindly pointed out by Daniel.  There was
certainly no promise, however, that this was the *only* error.

The remaining "memory leak" is caused by the totally incorrect handling
of cur_node->properties, which is basically corrupting the internal tree.
 One way of correcting this particular error would be to replace the
"while" loop code with:

   xmlAttrPtr propPtr;
     ....
       propPtr = cur_node->properties;
       while( propPtr ) {
           key = (xmlChar*) propPtr->name;
           value = xmlGetProp( cur_node, key);
           printf("%s/%s = %s\n", category, key, value);
           xmlFree(value);
           propPtr = propPtr->next;
       }

Note, however, that there is still *no guarantee* that there are not
other errors within your code.

Regards,

Bill

Taeyoung Hong wrote:

I tested the following YuChan's test code by adding "xmlFree(value)"
in while loop like this;

               while( cur_node->properties ) {
                        key = (xmlChar*) cur_node->properties->name;
                        value = xmlGetProp( cur_node, key);
                        printf("%s/%s = %s\n", category, key, value);
                        xmlFree(value);
                        cur_node->properties =
cur_node->properties->next;
                }

However, still memory leak occurs.
On one hundred iteration of test() fuction in the code, resident
memory size of the program increased up to 88 KB.
testbed is the linux w/ 2.6.9-5.0.5.ELsmp, x86_64, opteron, CentOS 4.0,
and rpm libxml2-2.6.16-6 was installed

the same test without xmlFree(value) gives the 96 KB memory leaks.

when I tried to test the simplified code like this, which gave us the
same result,
88KB memory leaks,

               while( cur_node->properties ) {
                                            cur_node->properties =
cur_node->properties->next;
                }

I do not know where this leak comes from.
Plz, let me know that






------------------------------------------------
Re: [xml] Help: memory leak ??
Daniel Veillard
Tue, 22 Aug 2006 02:58:06 -0700
On Tue, Aug 22, 2006 at 05:07:27PM +0900, YuChan Park wrote:

during running the program it comsume 8 or 4 bytes memory whenever call
test
function included in blow code.

...

                       value = xmlGetProp( cur_node, key);


  http://xmlsoft.org/html/libxml-tree.html#xmlGetProp

  Returns:      the attribute value or NULL if not found. It's up to the
caller
to free the memory with xmlFree().

  no amount of asking will ever replace reading the docs.

Daniel

--
Red Hat Virtualization group http://redhat.com/virtualization/
Daniel Veillard      | virtualization library  http://libvirt.org/
[EMAIL PROTECTED]  | libxml GNOME XML XSLT toolkit  http://xmlsoft.org/
http://veillard.com/ | Rpmfind RPM search engine  http://rpmfind.net/


----------------------------------------------------------------------------------------------------------------

[xml] Help: memory leak ??

YuChan Park
Tue, 22 Aug 2006 01:07:39 -0700
Hello.

I wrote some application with libxml2 ( version 2.6.23 ).

but the application comsume the system memory

So for testing i tried to run example program which was written as
like my program.
but the status is same .

during running the program it comsume 8 or 4 bytes memory whenever
call test function included in blow code.

the memory status is observated using top( linux program)

RES included in top is increased continuously during running program..

why does this problem appear??

thanks.

------------------CODE---------------------------------------------
#include <stdio.h>
#include <libxml/parser.h>
#include <libxml/tree.h>
#include <string.h>


char *testxml = "<GETINFO><NODENAME name=\"main.diylinux.org\"
command=\"GETINFO\" /> \
                  <cpu load=\"3010.714\" /> \
                  <UPTIME>53768.39 52310.89</UPTIME></GETINFO>";

static void
print_element_names(xmlNode * a_node)
{
    xmlNode *cur_node = NULL;
    xmlChar *key;
    xmlChar *category;
    xmlChar  *keys;
    xmlChar *value;

    for (cur_node = a_node; cur_node; cur_node = cur_node->next) {

        if (cur_node->type == XML_ELEMENT_NODE) {

                category = (xmlChar*)cur_node->name;
                while( cur_node->properties ) {
                        key = (xmlChar*) cur_node->properties->name;
                        value = xmlGetProp( cur_node, key);
                        //printf("%s/%s = %s\n", category, key, value);

                        cur_node->properties =
cur_node->properties->next;
                }
        }

        print_element_names(cur_node->children);
    }

}


int
test()
{
    xmlDoc *doc = NULL;
    xmlNode *root_element = NULL;

    //if (argc != 2)
     //   return(1);

    LIBXML_TEST_VERSION

    /*parse the file and get the DOM */
    //doc = xmlReadFile(argv[1], NULL, 0);
    doc = xmlParseMemory( testxml, strlen( testxml ) );

    if (doc == NULL) {
        return 1;
    }

    /*Get the root element node */
    root_element = xmlDocGetRootElement(doc);
    print_element_names(root_element);

    xmlFreeDoc(doc);

     xmlCleanupParser();

    return 0;
}


int main(void)
{
        int i;
        for( i =0; i<100; i++) {
                test();
                sleep(1);
        }
        return 0;
}

-------------------------------------------------END CODE--------------
compile:
gcc -o ttest test.c `libxml2-config --cflags --libs`

./ttest

status: top -p `pidof ttest`
the RES in top  increased continuously
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