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From "Grzegorz Kossakowski (JIRA)" <j...@apache.org>
Subject [jira] Commented: (COCOON-2216) IncludeCacheManager can not perfom parallel includes
Date Thu, 02 Oct 2008 13:31:45 GMT

    [ https://issues.apache.org/jira/browse/COCOON-2216?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12636361#action_12636361
] 

Grzegorz Kossakowski commented on COCOON-2216:
----------------------------------------------

Imran,

It's my time to apologize. I didn't read your previous description carefully enough. Now I
could reproduce your problem which is just a sign of much bigger problem.

IncludeCacheManager uses thread pooling technique which does not play nicely with ThreadLocals,
see: http://java.sys-con.com/node/37241

As I said this problem is not limited to the newly introduced Factory for ObjectModel. Servlet
Service Fw and Spring itself use ThreadLocals as well.

I think this is a right time to move this discussion to dev@ list so others can comment. I'll
be probably in favour of removing thread pooling completely but I don't know performance implications
at the moment.

> IncludeCacheManager can not perfom parallel includes
> ----------------------------------------------------
>
>                 Key: COCOON-2216
>                 URL: https://issues.apache.org/jira/browse/COCOON-2216
>             Project: Cocoon
>          Issue Type: Bug
>          Components: - Components: Sitemap
>    Affects Versions: 2.2-dev (Current SVN)
>            Reporter: Christoph Gaffga
>            Assignee: Grzegorz Kossakowski
>         Attachments: cocoon-trunk.patch, multi-thread-simple-28.09.2008.patch, ParallelInclusionProblem-cocoon_TRUNK.patch,
test-block.zip, test-block.zip, test-webapp.zip, test-webapp.zip
>
>
> Since we migrated from cocoon 2.1 to 2.2 a generator that merges multiple sources from
other cocoon pipelines into one (similar to the aggregator) is not working anymore.
> We also posted our problem to the mailing list, got little feedback but it brought us
on the right way...
> see also: http://www.mail-archive.com/users@cocoon.apache.org/msg42173.html
> I found out that it's a problem with the DefaultIncludeCacheManager, that can not do
parallel inclusion of cocoon-pipelines anymore. I checked several classes where inclusion
is used. In the aggregator parallel inclusion is not an option anymore, in CIncludeTransformer
the IncludeCacheManager is used, but it can't do parallel inclusion. In the new IncludeTransfomer
parallel inclusion is supported, but it does not use caching as it does not use the IncludeCacheManager...
> But we needed caching AND parallel processing, so I tried to find out what's broken in
the DefaultIncludeCacheManager:
> and it seems that the ThreadLocal variables are not initialized for the child threads
that do the inclusion. Neither the spring context nor the old environment stuff was initialized.
And all the source resolving was done outside the child thread and that way using the wrong
thread context. 
> We were able to fix that issue by small changes to DefaultIncludeCacheManager and IncludeCacheManagerSession.
It would be great if somebody could apply this patch so we don'T have to patch every cocoon
version again and again...

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