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Posted to derby-dev@db.apache.org by "Knut Anders Hatlen (JIRA)" <ji...@apache.org> on 2013/07/16 10:20:50 UTC

[jira] [Commented] (DERBY-5730) DataDictionaryImpl leaks references to itself via SYSFUN_AD

    [ https://issues.apache.org/jira/browse/DERBY-5730?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13709599#comment-13709599 ] 

Knut Anders Hatlen commented on DERBY-5730:
-------------------------------------------

The required execute permission was added to derby_tests.policy in 10.9 as part of DERBY-4249.
                
> DataDictionaryImpl leaks references to itself via SYSFUN_AD
> -----------------------------------------------------------
>
>                 Key: DERBY-5730
>                 URL: https://issues.apache.org/jira/browse/DERBY-5730
>             Project: Derby
>          Issue Type: Bug
>          Components: Services
>    Affects Versions: 10.9.1.0
>            Reporter: Knut Anders Hatlen
>            Assignee: Knut Anders Hatlen
>             Fix For: 10.9.1.0
>
>         Attachments: d5730-1a.diff, DERBY5730_backport_patch1_diff.txt, Sysfun.java, SysfunPerftest.java
>
>
> DataDictionaryImpl contains a static field called SYSFUN_AD, which holds an array of AliasDescriptor objects for the functions in the SYSFUN schema. This array is lazily populated as the functions are called, and it is shared between all DataDictionaryImpl instances on the system.
> The AliasDescriptors contain references to the DataDictionaryImpl that created them, so SYSFUN_AD may end up referencing indirectly to a number of different DataDictionaryImpl instances, depending on where the respective SYSFUN functions are called the first time. Once an AliasDescriptor has been added to SYSFUN_AD, it stays there until the DataDictionaryImpl class is unloaded (in most cases, until the JVM terminates). This means the array may hold references to DataDictionaryImpl instances that belong to database instances that have been shut down, and that the memory held by those database instances never becomes eligible for garbage collection.

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