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From "Robin Green" <gree...@hotmail.com>
Subject Re: Xalan caching...
Date Sat, 02 Sep 2000 18:46:45 GMT
Duncan Alexander <Duncan.Alexander@vcint.com> wrote:
>I know this question has been asked before but I failed to find a
>'definitive' answer.
>
>Does Xalan cache compiled XSLT pages and if it does not....does it store 
>the
>uncompiled XSLT page in memory?

I don't know, but I do know that Cocoon caches XSLT - even if you try to 
turn caching off in cocoon.properties or by setting the request parameter 
cache=false. This is because it bypasses the Cache object and goes straight 
to the Store.

I know, the design of Cocoon 1 cacheing isn't perfect!

>The reason I ask is that when using memory profiling tools I can see a
>significant number of new DOM related objects being
>held in memory when making Cocoon requests (with cocoon cache switched 
>off).
>When forcing refreshes
>of the relevant pages those objects do not get recreated. The only thing I
>can assume is that Xalan is
>performing some kind of caching.

Cocoon is, certainly. In theory there is a Store cleanup thread, and a 
backup OutOfMemoryError handler which will try to rescue the situation if 
that fails, to prevent out of memory errors. However we have had 
intermittent OutOfMemoryErrors until I reprogrammed MemoryStore to use a 
JDK1.2 WeakHashMap instead, and disabled auto-reloading for most of our 
in-house classes (this auto-reload feature is not even present in cocoon 
yet, but it will be - with a warning in the documentation about memory 
consumption!) For example if an OutOfMemory error occurs outside Cocoon, 
Cocoon cannot come to the rescue (at least, temporarily).

Cocoon 2 will be much more resilient in terms of memory usage because it 
will use a WeakHashMap or something like it for caching.


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