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From Antonio Gallardo <agalla...@agssa.net>
Subject Re: [jira] Reopened: (COCOON-1799) [PATCH] Threads waste when reading a not found resource.
Date Fri, 10 Mar 2006 23:20:28 GMT
Jean-Baptiste Quenot (JIRA) wrote:

>     [ http://issues.apache.org/jira/browse/COCOON-1799?page=all ]
>     
>Jean-Baptiste Quenot reopened COCOON-1799:
>------------------------------------------
>
>
>I'm reopening this issue just for trunk: AbstractCachingProcessingPipeline locking feature
*must* be ported to trunk, and this bugfix as well.
>  
>
IMHO given the current code base, the bug has already been fixed 
everywhere. The bug was introduced with the newly "locking feature". 
Note the bug was only for 2.1.x-dev and since the code has not been 
merged in 2.2 yet, actually it does not apply for 2.2. When the trunk 
will be synchronized, this bug will be automatically fixed there too, 
hence the bug has never been nor will appear in 2.2.

On the other side, if what we wanted to point out was a reminder that 
the code needs to be marge for this class in 2.2, I think this bug 
report is the worse place to put this kind of reminder. If a reminder is 
necesary, then please open a new bug with the correct description: 
"Merge 'AbstractCachingProcessingPipeline.java' code from 2.1 in 2.2" or 
something like that.

BTW, We committers should merge our changes in branch to trunk to keep 
both synchronized. I know this is a boring task, but an important one.

wdyt?

Best Regards,

Antonio Gallardo.

>  
>
>>[PATCH] Threads waste when reading a not found resource.
>>--------------------------------------------------------
>>
>>         Key: COCOON-1799
>>         URL: http://issues.apache.org/jira/browse/COCOON-1799
>>     Project: Cocoon
>>        Type: Bug
>>  Components: * Cocoon Core
>>    Versions: 2.1.9-dev (current SVN)
>>    Reporter: Simone Gianni
>>    Assignee: Antonio Gallardo
>>    Priority: Blocker
>>     Fix For: 2.1.9-dev (current SVN)
>> Attachments: pipeline.diff
>>
>>When setting up a pipeline with a reader on a not found file, the first time a 404
is reported, but following requests will hang up and the thread will never get released, causing
a potential complete lock exausting threads.
>>In the AbstractCachingProcessingPipeline class, in ProcessReader method, the following
happens :
>>- 774: a pcKey is created for caching content
>>- 853: the method eventually waits if another thread is generating
>>- 869: the method acquires a lock, to avoid other threads to generate twice
>>- 886: if there is no need cache validity pcKey is setted to null
>>- 918: if an exception occurrs while generating, the following code is in a finally
:
>>            		if (pcKey != null) {
>>            			releaseLock(pcKey);
>>            		}
>>This obviously brings to the following situation :
>>- A non existing resource is being generated
>>- A lock is acquired
>>- The FileSource returns null if the file does not exist.
>>- So pcKey is setted to null.
>>- An exception is thrown, since the file is not found.
>>- The finally block does not release the lock
>>- Next requests on the same file will hang waiting on the lock, but the other thread
will never release it.
>>This can easily consume all threads, it's quite easy to have this kind of errors on
a missing gif, or css, or favicon.ico or something else. 
>>I modified this class so that it :
>>- Does not set pckey to null when readerValidity == null
>>- Checks for pckey != null && readerValidity != null on line 907 so that content
is not cached if readerValidity == null
>>- Since pckey is != null the lock is released.
>>I tested it and seems to work correctly, but this is core stuff, please double check
it!!
>>    
>>
>
>  
>


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