Cocoon Performance settings

["Linczak, Jonathan W." <Li...@hiram.edu>]

Hi,

I'm confused on some of the settings specified for the store janitor in cocoon.xconf.  According to the Wiki doc here: http://wiki.apache.org/cocoon/CocoonPerformanceResults, the following values are set for freememory and heapsize:

freememory: 20000000
heapsize: 80000000

where the JVM is started with a max heap size of 2536 MB.  This seems to be in stark constrast to what the recommendations are for these values.  For example, this document in the Excalibur project: http://excalibur.apache.org/store/janitor.html, does a good job of explaining the recommended values.  Here, the heapsize in the store janitor should be set to 2% less of the max heap size for the JVM.  The freememory should be set to whatever is necessary to run the application.  So, shouldn't freememory and heapsize be the following:

freememory: ?? (this should depend on how large your Cocoon webapp is, right?)
heapsize: 2536 * 1024 * 1024 * 0.98 ~= 2600000000

My questions are:

1.  Why choose such a low value for the freememory?  I don't understand where the ~19 MB value (20000000) comes from.  Is this all that is needed to keep Cocoon going?

2.  Why choose such a low value for the heapsize?  What was the reason for deviating from the recommended values?

3.  Why choose 2536 MB as the max heap size for the JVM?  Was this arrived at by much testing, or because some formula was used to compare against the rest of the system memory?

Jon