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http://issues.apache.org/jira/browse/JS2-226?page=comments#action_12431771 ] 
            
David Sean Taylor commented on JS2-226:
---------------------------------------

Hi Woonsan,

I was planning on working on the parallel strategy in September for the 2.1 
release. My schedule has slipped a little though, so Im encouraged to hear 
someone else show interest in the parallel strategy.

I wouldn't be put off by the performance.
There are some very valuable use cases that make the parallel strategy 
valuable. If all of your portlets are simply retrieving small snippets of 
content, and displaying them, there will be no advantage. In fact, the overhead 
will make the overall aggregation slower. I would think that we would want to 
make use of hints to help with the parallel aggregation process, such as 
statistical analysis and configuration. With configuration, a portlet can be 
marked as requiring parallel. With statistics, we can keep track of which 
portlets are slow, and move those into thread groups based on their historical 
performance.

The key use case for parallel rendering is when one or more portlets are taking 
a lot longer than other portlets to render, then the other portlets will not 
have to wait on them as they do in the sequential strategy. Additionally, we 
can put a ms threshold on all portlet threads returning, so that if a portlet 
takes more than say 4000 ms, we override  the content with "Portlet Not 
Available" and return the entire response stream. The thread will have to be 
collected later. 

I think your idea, of storing attributes in the worker, is sound.
In my testing, I also discovered that Tomcat requests are not thread-safe.

We are actually solving this problem from two different approaches in 2.1. 
Parallel rendering on the server is on approach. The second approach is 
parallel rendering on the client, with the Jetspeed Desktop.
The Desktop solution distributes the aggregation process onto clients. 

Anyway, I'd be very happy to work with you on this.
 


> Page Aggregation using STRATEGY_PARALLEL severly broken
> -------------------------------------------------------
>
>                 Key: JS2-226
>                 URL: http://issues.apache.org/jira/browse/JS2-226
>             Project: Jetspeed 2
>          Issue Type: Bug
>          Components: Aggregation
>    Affects Versions: 2.1
>         Environment: Tomcat 5.0.28
>            Reporter: Ate Douma
>         Assigned To: David Sean Taylor
>            Priority: Critical
>
> While trying to evaluate the status of JS2-17 I tested PageAggregation with 
> PageAggregatorImpl.STRATEGY_PARALLEL and the effect is a total breakdown!
> I'll look into this AFTER the M2 release.
> Not sure if the current problem is related to JS2-17 but I'll check that too.

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