[jira] Updated: (DERBY-2700) Invalid entries in the cache manager are not garbage collected until the CachedItem is reused

["Knut Anders Hatlen (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/DERBY-2700?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Knut Anders Hatlen updated DERBY-2700:
--------------------------------------

    Attachment: 2700.diff

The attached patch (2700.diff) sets CachedItem.entry to null when it is marked as invalid. I have not run the full regression test suite, but I have verified (by monitoring the process with JConsole) that Derby is able to free a lot more memory after dropping a table with this patch.

> Invalid entries in the cache manager are not garbage collected until the CachedItem is reused
> ---------------------------------------------------------------------------------------------
>
>                 Key: DERBY-2700
>                 URL: https://issues.apache.org/jira/browse/DERBY-2700
>             Project: Derby
>          Issue Type: Bug
>          Components: Services
>    Affects Versions: 10.2.1.6, 10.2.2.0, 10.3.0.0
>            Reporter: Knut Anders Hatlen
>         Assigned To: Knut Anders Hatlen
>         Attachments: 2700.diff
>
>
> When an entry in the cache manager becomes invalid (for instance because a table is dropped), it cannot be garbage collected because we only set the valid_ field in CachedItem to false. We should also set entry to null to make the Cacheable eligible for garbage collection. Currently, invalid cached objects cannot be garbage collected until their CachedItems are reused. This causes Derby to hold on to resources too long, and can in the worst case lead to an OutOfMemoryError.

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