XSLT Cache Behavior

[Arlo White]

portal.properties has the following section

# Controls whether or not pre-compiled stylesheets should be cached.
# Setting this to "on" improves performance, but then changes to
# any stylesheet files (.xsl) will not take effect until
# the portal has been restarted.
#
org.jasig.portal.utils.XSLT.stylesheet_root_caching=on

This seems to indicate that .xsl files are cached permanently. However,
some of our that channels pull in xsl files externally seem to update
after a file change in about 4 hours. How does XSL caching work in the
portal? Does the caching behavior change depending on whether the xsl
files are local or external?

To be clear, I'm talking about native uPortal channels where the .ssl
file has external and/or internal urls, for example:
<?xml-stylesheet title="viewRecord"
href="http://calpoly.edu/some/external/source/file.xsl" type="text/xsl"
media="all"?>
<?xml-stylesheet title="viewHelp"
href="/edu/calpoly/internal/channel/file.xsl" type="text/xsl"
media="netscape"?>

[awhite.vcf]

---

begin:vcard
fn:Arlo White
n:White;Arlo
org:ITS;Application Integration
adr;dom:Calpoly;;Chase Hall, Room 215;San Luis Obispo;CA
email;internet:[hidden email]
title:Analyst/Programmer
tel;work:[phone]
x-mozilla-html:TRUE
version:2.1
end:vcard

---