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Posted to derby-dev@db.apache.org by "Kim Haase (JIRA)" <ji...@apache.org> on 2008/08/05 20:36:44 UTC
[jira] Closed: (DERBY-3612) Developer's Guide needs correction on
garbage collection
[ https://issues.apache.org/jira/browse/DERBY-3612?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Kim Haase closed DERBY-3612.
----------------------------
> Developer's Guide needs correction on garbage collection
> --------------------------------------------------------
>
> Key: DERBY-3612
> URL: https://issues.apache.org/jira/browse/DERBY-3612
> Project: Derby
> Issue Type: Bug
> Components: Documentation
> Affects Versions: 10.3.2.1
> Reporter: Kim Haase
> Assignee: Kim Haase
> Priority: Minor
> Fix For: 10.4.2.0, 10.5.0.0
>
> Attachments: DERBY-3612.diff, tdevdvlp20349.html
>
>
> In a comment on DERBY-3585, Martin Zaun pointed out the following error:
> devguide/tdevdvlp20349.dita
> - found a flatly wrong statement but did NOT correct here since
> unrelated to server shutdown authentication:
> "You cannot explicitly request that the JVM unload a class, but you
> can ensure that the EmbeddedDriver class is unloaded by using a
> System.gc() to force it to garbage collect classes that are no longer
> needed. Running with -nogc or -noclassgc definitely prevents the class
> from being unloaded and makes you unable to restart Derby in the same
> JVM."
> System.gc() is only a suggestion to the Runtime to garbage-collect, it
> cannot be enforced, and there's no guarantee whatsoever that GC has
> run and any classes been unloaded. Likewise it's most probably not
> guarantueed that -nogc or -noclassgc definitely (!) prevent a class
> from being unloaded (a JVM may ignore these options...)
> This needs to be fixed. Thanks, Martin.
> One more question: are -nogc and -noclassgc java command line options, or options to some other command? I can't find them in the java command documentation -- http://java.sun.com/javase/6/docs/technotes/tools/windows/java.html. There is an -Xnoclassgc option, however.
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