[jira] Commented: (OPENJPA-219) Reflection: negative caching would be beneficial in redeployment scenarios

["Patrick Linskey (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/OPENJPA-219?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12489536 ] 

Patrick Linskey commented on OPENJPA-219:
-----------------------------------------

Note that we invoke Class.getDeclaredField() (and Class.getDeclaredMethod()) in a number of places. We should take care to replace all the uses of that method with our optimized version.

> 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
>
>
> 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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