[COCOON-1574] Memory Leak with XMLFileModule

• Type: Bug
• Status: Reopened
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: 2.2
• Fix Version/s: 2.1.11
• Component/s: * Cocoon Core
• Environment: Operating System: Windows XP; Platform: PC
• Bugzilla Id: 36162
• Affects version (Component): Components: Sitemap
• Fix version (Component): Components: Sitemap
• Assignee: Unassigned
• Reporter: Ronald Blaschke
• Created: 12/Aug/05 21:54
• Updated: 23/May/14 04:42

Description

I'm currently looking into a memory leak issue at Apache Forrest. Forrest's
site currently needs to be built with -Xmx128m because of this. I believe the
issue is originated at Cocoon's LinkRewriterTransformer or XMLFileModule.

A memory profiler shows lots (30MB+) of DOM DocumentImpls (150+ objects), which
get referenced by XMLFileModule.DocumentHelper. Their URIs are linkmap-xxx.

LinkRewriterTransformer#createTransformedLink(String) uses a InputModuleHelper,
which seems to reference a XMLFileModule.
  ...
  newLink = (String) modHelper.getAttribute(this.objectModel,
                     ^^^^^^^^^
  ...

The XMLFileModule keeps the visited documents in a map, which is where they
build up.

Just for testing, I changed XMLFileModule#getDocumentHelper(Configuration) from
  this.documents.put(src, new DocumentHelper(reload, cache, src, this));
to
  return new DocumentHelper(reload, cache, src, this);

Thus, a new DocumentHelper is created every time, instead of caching them. The
result: No more memory problems, Apache Forrest's site builds again with -Xmx32.

Ron

Issue Links

• blocks: FOR-591 MaxMemory needs increasing for large document sets: Memory Leak with XMLFileModule