avoid memory leak in xend

Hi,

Attached patch removes a memory leak in xend.

Juergen

Juergen Gross                 Principal Developer Operating Systems
TSP ES&S SWE OS6                       Telephone: +49 (0) 89 636 47950
Fujitsu Technolgy Solutions               e-mail: [email protected]
Otto-Hahn-Ring 6                        Internet: ts.fujitsu.com
D-81739 Muenchen                 Company details: ts.fujitsu.com/imprint.html

Memory leak in Xend, resulting in long garbage collector runs.

In the method xen.xend.XendStateStore.XendStateStore.load_state and xen.xend.XendStateStore.XendStateStore.save_state the minidom objects used to load/save the current state of a device type, can't be freed by the python garbage collector after all references to the top node are cleared, because of cyclic references between the DOM nodes. So memory usage of xend increases after calling these methods.
To solve this problem, the unlink() method must be called for a minidom object before the last reference to the top node is cleared (see python docs). This breaks the cyclic references, so the garbage collector can free these objects.

# HG changeset patch
# User [email protected]
# Date 1249300432 -7200
# Node ID d40abdac1cf42ae552f727750cd0cca0b8d32361 # Parent 41b2c4e4f6746c638192b88ea37d3d25196850ad Avoid memory leak in xend

diff -r 41b2c4e4f674 -r d40abdac1cf4 tools/python/xen/xend/XendStateStore.py
@@ -147,6 +147,7 @@
                     cls_dict[val_name] = bool(int(val_text))
             state[uuid] = cls_dict
 
+        dom.unlink()
         return state
 
     def save_state(self, cls, state):

@@ -226,5 +227,5 @@
                     node.appendChild(val_node)
 
         open(xml_path, 'w').write(doc.toprettyxml())
-        
+        doc.unlink()
     

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