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From "Miguel Cuervo (JIRA)" <j...@apache.org>
Subject [jira] Updated: (COCOON-2109) Incorrent cleanup of expired continuations
Date Fri, 10 Aug 2007 12:11:42 GMT

     [ https://issues.apache.org/jira/browse/COCOON-2109?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Miguel Cuervo updated COCOON-2109:
----------------------------------

    Description: 
The class ContinuationsManagerImpl is in charge of cleaning up expired continuations. It does
so in the method expireContinuations. In this method there is a loop using an iterator over
a SortedSet of continuations (WebContinuation). The loop is expecting that the continuations
are ordered from oldest to newest.  The loop stops in the first continuation that is not expired.
The logic is correct since all the newer continuations could not be expired.

However, the problem comes from the ordering of the continuations. To have the continuations
ordered by lastAccessTime the program uses a TreeSet as a container of the continuations.
The continuations implement the compareTo interface using the lastAccessTime and when a continuation
is inserted in the container, it gets correctly ordered. But after the insertion, the continuation
can change its lastAccessTime using the method WebContinuation.updateLastAccessTime() called
from WebContinuation.getContinuation(). The ordering of the TreeSet is not updated with the
change and when the program iterates over it, it does not get the continuations in the order
expected.

The result of this bug is that under hevy load many expired continuations may be around before
the loop actually clean them up, eating memory resources and causing OutOfMemory.

To fix it, a patch is provided that uses a HashSet for the continuations container and loops
over all the continuations to check if they have expired.



  was:
The class ContinuationsManagerImpl is in charge of cleaning up expired continuations. It does
so in the method expireContinuations. In this method there is a loop using an iterator over
a SortedSet of continuations (WebContinuation). The loop is expecting that the continuations
are ordered from oldest to newest.  The loop stops in the first continuation that is not expired.
The logic is correct since all the newer continuations could not be expired.

However, the problem comes from the ordering of the continuations. To have the continuations
ordered by lastAccessTime the program uses a TreeSet as a container of the continuations.
The continuations correctly implement the compareTo interface using the lastAccessTime and
when a continuation is inserted in the container, it gets correctly ordered. But once the
continuation is inserted in the container, the continuation can change its lastAccessTime
using the method WebContinuation.updateLastAccessTime() called from WebContinuation.getContinuation().
The ordering of the TreeSet is not updated with the change and when the program iterates over
it, it does not get the continuations in the order expected.

The result of this bug is that under hevy load may expired continuations may be around before
the loop actually clean them up, eating memory resources and causing OutOfMemory.

To fix it, a patch is provided that uses a HashSet for the continuations container and loops
over all the continuations to check if they have expired.




> Incorrent cleanup of expired continuations
> ------------------------------------------
>
>                 Key: COCOON-2109
>                 URL: https://issues.apache.org/jira/browse/COCOON-2109
>             Project: Cocoon
>          Issue Type: Bug
>          Components: - Flowscript
>    Affects Versions: 2.1.6, 2.1.7, 2.1.8, 2.1.9, 2.1.10, 2.1.11-dev (Current SVN)
>            Reporter: Miguel Cuervo
>         Attachments: ContinuationsManagerImpl.java.patch
>
>
> The class ContinuationsManagerImpl is in charge of cleaning up expired continuations.
It does so in the method expireContinuations. In this method there is a loop using an iterator
over a SortedSet of continuations (WebContinuation). The loop is expecting that the continuations
are ordered from oldest to newest.  The loop stops in the first continuation that is not expired.
The logic is correct since all the newer continuations could not be expired.
> However, the problem comes from the ordering of the continuations. To have the continuations
ordered by lastAccessTime the program uses a TreeSet as a container of the continuations.
The continuations implement the compareTo interface using the lastAccessTime and when a continuation
is inserted in the container, it gets correctly ordered. But after the insertion, the continuation
can change its lastAccessTime using the method WebContinuation.updateLastAccessTime() called
from WebContinuation.getContinuation(). The ordering of the TreeSet is not updated with the
change and when the program iterates over it, it does not get the continuations in the order
expected.
> The result of this bug is that under hevy load many expired continuations may be around
before the loop actually clean them up, eating memory resources and causing OutOfMemory.
> To fix it, a patch is provided that uses a HashSet for the continuations container and
loops over all the continuations to check if they have expired.

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