DO NOT REPLY [Bug 30162] New: - [PATCH] Avoid potential memory leaks from IntrospectionHelper.helpers

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http://issues.apache.org/bugzilla/show_bug.cgi?id=30162

[PATCH] Avoid potential memory leaks from IntrospectionHelper.helpers

           Summary: [PATCH] Avoid potential memory leaks from
                    IntrospectionHelper.helpers
           Product: Ant
           Version: 1.6.1
          Platform: All
        OS/Version: All
            Status: NEW
          Severity: Normal
          Priority: Other
         Component: Core
        AssignedTo: dev@ant.apache.org
        ReportedBy: jglick@netbeans.org


IntrospectionHelper keeps a cache of helpers it has made for particular Class's.
This cache is cleared (presumably to avoid leaking memory) when the build
finishes - *if* callers have used the factory method IH.getHelper(Project,Class)
rather than the IH.gH(Class) variant. Unfortunately, if you call only
IH.gH(Class) then the Class references are not released, even by a build finish
event.

This appears to have caused a massive memory leak in the JVM permanent
generation (where classes are held) in the NetBeans IDE. (Workaround: forcibly
clear the cache via reflection.) More:
http://www.netbeans.org/issues/show_bug.cgi?id=43113

Better would be to use a WeakHashMap, since there is no reason to keep a cache
entry if the Class key is referenced only from that entry; it could not possibly
be used. Generally, please be very suspicious of any static fields, especially
maps, and use weak references wherever appropriate.

Attaching a patch which makes the cache weak on the key, and also uses the 2-arg
variant of getHelper wherever it seems it would be possible. (There are some
places where there is no Project context and it is not possible.)

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