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https://issues.apache.org/jira/browse/COCOON-2173?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Alexander Daniel updated COCOON-2173:
-------------------------------------
Attachment: patchFor2.1.11.txt
For applying the patch to Cocoon 2.1.11 use patch -p6
<$DownloadFolder/patchFor2.1.11.txt
I considered three possibilities to fix this issue
(1) using a timed wait
(2) removing the synchronization of requests with pipe locks completely
(3) redesign of the synchronization of requests
I chose (1) for simplicity. The current waitForLock implementation returns true
when the lock is the current thread (request for 2.1-dev and 2.2-dev). For the
calling method validatePipeline this means that there was no cached response
found. When there is a timeout on the timed wait it behaves the same way. The
default timeout is 250ms but it can be configured with the
timeoutForSynchronizingRequests parameter.
Unit tests for the new method timedWait are included in patchFor2.1.11.txt
> AbstractCachingProcessingPipeline: Two requests can deadlock each other
> -----------------------------------------------------------------------
>
> Key: COCOON-2173
> URL: https://issues.apache.org/jira/browse/COCOON-2173
> Project: Cocoon
> Issue Type: Bug
> Components: - Components: Sitemap
> Affects Versions: 2.1.9, 2.1.10, 2.1.11, 2.2-dev (Current SVN)
> Reporter: Alexander Daniel
> Attachments: patchFor2.1.11.txt, reproduceMultipleThreads.tar.gz,
> reproduceMultipleThreads2.2RC3-SNAPSHOT.tar.gz
>
>
> Two requests can deadlock each other when they depend on the same resources
> which they acquire in a different order. I can reproduce that in Cocoon
> 2.1.11 and Cocoon 2.2-RC3-SNAPSHOT:
> * request A: generating lock for 55933
> * request B: generating lock for 58840
> * request B: waiting for lock 55933 which is hold by request A
> * request A: waiting for lock 58840 which is hold by request B
> I can reproduce this behaviour with Apache Bench and following pipeline:
> * terminal 1: Apache Bench request A (ab -k -n 10000 -c 25
> http://localhost:8888/samples/reproduceMultipleThreads/productOfferForDevice/55933/)
>
> * terminal 2: Apache Bench request B (ab -k -n 10000 -c 25
> http://localhost:8888/samples/reproduceMultipleThreads/productOfferForDevice/58840/)
>
> * terminal 3: touching the two data files every second to invalidate the
> cache (while true; do echo -n "."; touch 55933.xml 58840.xml; sleep 1; done)
> * pipeline:
> <map:pipeline type="caching">
> <map:match pattern="productOfferForDevice*/*/">
> <map:generate src="cocoon:/exists/{2}.xml" label="a"/>
> <map:transform type="xsltc" src="productOfferIncludeDevice.xsl"
> label="b">
> <map:parameter name="noInc" value="{1}"/>
> </map:transform>
> <map:transform type="include" label="c"/>
> <map:serialize type="xml"/>
> </map:match>
> <map:match pattern="exists/**">
> <map:act type="resource-exists">
> <map:parameter name="url" value="{1}" />
> <map:generate src="{../1}" />
> <map:serialize type="xml" />
> </map:act>
> <!-- not found -->
> <map:generate src="dummy.xml" />
> <map:serialize type="xml" />
> </map:match>
> </map:pipeline>
> After some seconds the deadlock occurs ==>
> * Apache Bench requests run into a timeout
> * I can see following pipe locks in the default transient store:
> PIPELOCK:PK_G-file-cocoon://samples/reproduceMultipleThreads/exists/55933.xml?pipelinehash=-910770960103935149_T-xsltc-file:///Users/alex/dev/cocoon/cocoon-2.1.11/build/webapp/samples/reproduceMultipleThreads/productOfferIncludeDevice.xsl;noInc=_T-include-I_S-xml-1
> (class: org.mortbay.util.ThreadPool$PoolThread)
> PIPELOCK:PK_G-file-cocoon://samples/reproduceMultipleThreads/exists/58840.xml?pipelinehash=-4996088883111986478_T-xsltc-file:///Users/alex/dev/cocoon/cocoon-2.1.11/build/webapp/samples/reproduceMultipleThreads/productOfferIncludeDevice.xsl;noInc=_T-include-I_S-xml-1
> (class: org.mortbay.util.ThreadPool$PoolThread)
> PIPELOCK:PK_G-file-file:///Users/alex/dev/cocoon/cocoon-2.1.11/build/webapp/samples/reproduceMultipleThreads/55933.xml
> (class: org.mortbay.util.ThreadPool$PoolThread)
> PIPELOCK:PK_G-file-file:///Users/alex/dev/cocoon/cocoon-2.1.11/build/webapp/samples/reproduceMultipleThreads/58840.xml
> (class: org.mortbay.util.ThreadPool$PoolThread)
> I added some logging to AbstractCachingProcessingPipeline.java which
> reconfirms the explanations above:
> INFO (2008-03-13) 13:50.16:072 [sitemap]
> (/samples/reproduceMultipleThreads/productOfferForDevice/55933/)
> PoolThread-47/AbstractCachingProcessingPipeline: generating lock
> PIPELOCK:PK_G-file-cocoon://samples/reproduceMultipleThreads/exists/55933.xml?pipelinehash=-910770960103935149_T-xsltc-file:///Users/alex/dev/cocoon/cocoon-2.1.11/build/webapp/samples/reproduceMultipleThreads/productOfferIncludeDevice.xsl;noInc=_T-include-I_S-xml-1
>
> INFO (2008-03-13) 13:50.16:074 [sitemap]
> (/samples/reproduceMultipleThreads/productOfferForDevice/55933/)
> PoolThread-47/AbstractCachingProcessingPipeline: generating lock
> PIPELOCK:PK_G-file-file:///Users/alex/dev/cocoon/cocoon-2.1.11/build/webapp/samples/reproduceMultipleThreads/55933.xml
>
> INFO (2008-03-13) 13:50.16:075 [sitemap]
> (/samples/reproduceMultipleThreads/productOfferForDevice/58840/)
> PoolThread-6/AbstractCachingProcessingPipeline: generating lock
> PIPELOCK:PK_G-file-cocoon://samples/reproduceMultipleThreads/exists/58840.xml?pipelinehash=-4996088883111986478_T-xsltc-file:///Users/alex/dev/cocoon/cocoon-2.1.11/build/webapp/samples/reproduceMultipleThreads/productOfferIncludeDevice.xsl;noInc=_T-include-I_S-xml-1
>
> INFO (2008-03-13) 13:50.16:075 [sitemap]
> (/samples/reproduceMultipleThreads/productOfferForDevice/58840/)
> PoolThread-6/AbstractCachingProcessingPipeline: generating lock
> PIPELOCK:PK_G-file-file:///Users/alex/dev/cocoon/cocoon-2.1.11/build/webapp/samples/reproduceMultipleThreads/58840.xml
>
> INFO (2008-03-13) 13:50.16:281 [sitemap]
> (/samples/reproduceMultipleThreads/productOfferForDevice/58840/)
> PoolThread-6/AbstractCachingProcessingPipeline: waiting for lock
> PIPELOCK:PK_G-file-file:///Users/alex/dev/cocoon/cocoon-2.1.11/build/webapp/samples/reproduceMultipleThreads/55933.xml
>
> INFO (2008-03-13) 13:50.16:304 [sitemap]
> (/samples/reproduceMultipleThreads/productOfferForDevice/55933/)
> PoolThread-47/AbstractCachingProcessingPipeline: waiting for lock
> PIPELOCK:PK_G-file-file:///Users/alex/dev/cocoon/cocoon-2.1.11/build/webapp/samples/reproduceMultipleThreads/58840.xml
>
> Reproduce yourself with Cocoon 2.1.11:
> * download and extract Cocoon 2.1.11
> * cd $CocoonHome
> * ./build.sh
> * cd build/webapp/samples
> * tar -xzf $DownloadFolder/reproduceMultipleThreads.tar.gz
> * cd ../../..
> * ./cocoon.sh
> * open 3 terminals and cd into
> $CocoonHome/build/webapp/samples/reproduceMultipleThreads in each
> * dry run without invalidating the cache to see that everything is working:
> - terminal 1: ./terminal1.sh
> - terminal 2: ./terminal2.sh
> * run with invalidating the cache every seconds:
> - terminal 1: ./terminal1.sh
> - terminal 2: ./terminal2.sh
> - terminal 3: ./terminal3.sh
> * When Apache Bench has run into a timeout you can view the pipelocks with
> http://localhost:8888/samples/reproduceMultipleThreads/pipelocks
> Reproduce yourself with Cocoon 2.2RC3-SNAPSHOT:
> * svn checkout http://svn.apache.org/repos/asf/cocoon/trunk
> * mvn clean install
> * ./cocoon.sh
> * cd core/cocoon-webapp/target/work/blocks/cocoon-core-main-sample
> * tar -xzf $DownloadFolder/reproduceMultipleThreads2.2RC3-SNAPSHOT.tar.gz
> * open 3 terminals and cd into
> $CocoonTrunk/core/cocoon-webapp/target/work/blocks/cocoon-core-main-sample/reproduceMultipleThreads/
> in each
> * dry run without invalidating the cache to see that everything is working:
> - terminal 1: ./terminal1.sh
> - terminal 2: ./terminal2.sh
> * run with invalidating the cache every second:
> - terminal 1: ./terminal1.sh
> - terminal 2: ./terminal2.sh
> - terminal 3: ./terminal3.sh
> * When Apache Bench has run into a timeout you can view the pipelocks with
> http://localhost:8888/samples/core/reproduceMultipleThreads/pipelocks
> Since we are currently facing this issue on our production servers I would
> appreciate a hint on how to fix that issue in a good way.
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