[Exist-development] eXist caching in a large memory environment....

[Andrzej J. T. <an...@ch...>]

Hi all:

I was looking through our eXist log files and spotted this warning:

2010-06-25 15:19:25,333 [main] WARN  (DefaultCacheManager.java [<init>]:150) - The cacheSize="2024" setting in conf.xml
is too large. Java has only 3185792k available. Cache manager will not use more than 1592896k to avoid memory issues
which may lead to database corruptions.

Now, we're running eXist on a 64-bit Ubuntu platform (3.2GHz quad proessor with 12GB of DDR3 memory), and are using the
64bit server Sun JVM, with the max memory for the JVM set to 3.5GB.

It would seem to me that limiting the cache to 50% of the available JVM memory in this kind of a scenario doesn't make a
lot of sense, since there is a lot of memory allocated to the JVM.

Does eXist actually need 50% of all memory, regardless of the memory available, when gobs or memory are there?  Or is
there some fixed high-water mark of non-cache JVM memory that eXist needs to avoid database corruptions, which for large
JVMs would be much smaller than 50%?

I suspect that the code in DefaultCacheManager that limits the cache memory use to 50% in such large memory scenarios
might be a bit too simplistic and thus not leveraging the additional memory effectively for caching?

Just curious....

Thanks!

-- 
Andrzej Taramina
Chaeron Corporation: Enterprise System Solutions
http://www.chaeron.com