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From "ASF subversion and git services (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (DERBY-5730) DataDictionaryImpl leaks references to itself via SYSFUN_AD
Date Wed, 17 Jul 2013 17:12:52 GMT

    [ https://issues.apache.org/jira/browse/DERBY-5730?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13711292#comment-13711292
] 

ASF subversion and git services commented on DERBY-5730:
--------------------------------------------------------

Commit 1504205 from [~mamtas] in branch 'code/branches/10'
[ https://svn.apache.org/r1504205 ]

DERBY-5730 (DataDictionaryImpl leaks references to itself via SYSFUN_AD)
DERBY-5753: (Derby5730Test fails on Java 5)


Backporting to 10.8. Original fix contributed by Knut.
                
> 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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