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https://issues.apache.org/jira/browse/OPENJPA-219?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Bret Weinraub updated OPENJPA-219:
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Attachment: OPENJPA-219-NoLeak.patch
Includes a non-caching performance enhancement for Reflection.findField()
Other implementations held on to references to class objects in static
collections. If the class loader which created this Class went away (like an
application classloader during redeployment), this reference would prevent the
ClassLoader object and associated Class objects from being garbage collected,
which would have led to a memory leak.
This version is about 3X faster than the original for JRockit, and about 5X
faster for HotSpot.
> Reflection: negative caching would be beneficial in redeployment scenarios
> --------------------------------------------------------------------------
>
> Key: OPENJPA-219
> URL: https://issues.apache.org/jira/browse/OPENJPA-219
> Project: OpenJPA
> Issue Type: Bug
> Components: kernel
> Affects Versions: 0.9.0, 0.9.6, 0.9.7
> Reporter: Patrick Linskey
> Fix For: 0.9.8
>
> Attachments: OPENJPA-219-NoLeak.patch, OPENJPA-219.patch
>
>
> In a variety of situations, OpenJPA searches class hierarchies for fields.
> These searches invoke Class.getDeclaredField() in order to find non-public
> fields. This method throws an exception when it fails to find the specified
> field, and the exception creation is, as ever, slow.
> It would be useful to create a static (and thus per-classloader)
> Map<WeakReference<Class>,Collection<String>> of fields known not to be
> available in a given class.
> It may also be beneficial to maintain a cache of which fields *are* present
> in a given class, but this issue is being filed as a result of a demonstrated
> performance hit during deployment due to the lack of a negative cache. If we
> obtain quantitative data indicating that a positive cache would be useful, we
> might want to implement such a thing at that time.
> Trace 3 (2115 occurances): [excepti][00090] java/lang/NoSuchFieldException:
> domainName
> at
> java/lang/Class.getDeclaredField(Ljava/lang/String;I)Ljava/lang/reflect/Field;(Unknown
> Source)
> at
> org/apache/openjpa/enhance/Reflection.findField(Ljava/lang/Class;Ljava/lang/String;Z)Ljava/lang/reflect/Field;(Reflection.java:101)
> at
> org/apache/openjpa/util/ApplicationIds.toPKValues(Ljava/lang/Object;Lorg/apache/openjpa/meta/ClassMetaData;)[Ljava/lang/Object;
> (ApplicationIds.java:89)
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