[hibernate-issues] [Hibernate-JIRA] Commented: (HV-479) Implement an eviction strategy for BeanMetaDataCache

[Kevin Pollet (JIRA)]

    [ http://opensource.atlassian.com/projects/hibernate/browse/HV-479?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=44560#comment-44560 ] 

Kevin Pollet commented on HV-479:
---------------------------------

IMO, a concurrent map is better for a cache. I'm also wondering if it will work as expected because the cached meta-data holds a reference to the key. Maybe using a {{WeakReference}} will work but I'm not sure. I think we need further investigations. In the WeakHashMap javadoc:

{quote}
The value objects in a WeakHashMap are held by ordinary strong references. Thus care should be taken to ensure that value objects do not strongly refer to their own keys, either directly or indirectly, since that will prevent the keys from being discarded
{quote}

BTW, is this the better strategy? Why not use an other strategy like LRU or LFU?
If we use another strategy do we allow the user to configure it (Configuration object and/or property) or use it's own implementation?

> Implement an eviction strategy for BeanMetaDataCache
> ----------------------------------------------------
>
>                 Key: HV-479
>                 URL: http://opensource.atlassian.com/projects/hibernate/browse/HV-479
>             Project: Hibernate Validator
>          Issue Type: Improvement
>          Components: engine
>            Reporter: Gunnar Morling
>             Fix For: 4.3.0.next
>
>
> In {{BeanMetaDataCache}} we have a map from {{Class}} to {{BeanMetaDataImpl}}. Currently there is no eviction strategy for this cache meaning entries will never be removed once they were added to the cache and the {{ValidatorFactoryImpl}} holding the cache exists.
> In particular this means that the concerned class objects never can be garbage-collected. This might cause problems in long-running applications (especially as there is typically one long-living {{ValidatorFactory}} instance per application). Maybe {{WeakHashMap}} or similar might be useful here.

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