Dear Chris,
I am setting up a monitoring system for Tomcat servers and I am
looking
for hard limits in Tomcat servers in general.
I found a few so far: file descriptors, memory pools (ok, these are
jdk
limits) and thread pools.
Are there any other hard limits that I can run into?
I would call these soft limits, as they can be changed.
Ah, sorry for the confusion. I should have asked for limits that are
hard at run-time. Thread pool sizes may be editable, but they are
fixed once Tomcat runs.
What limits are relevant? For instance, Java doesn't allow you to have
any method with more than 64k of code. I suppose that's of little
consequence to a running JVM, since the code would never be loaded.
Yes, I ran into that limit for a generated servlet once. This is not
the kind of limit that I am looking for, as it is caught compile-time,
not run-time.
If you are going to count memory (heap?) and file descriptors, I
suppose
you could also count CPU time, since that is a limitable resource on
*NIX systems.
Hmm. It's really only useful if I can monitor both the maximum
available time and the used time. I have no idea how I would measure
that, even at unix level. It gets even more messy in virtual servers.
If you really are talking about soft limits, then you probably also
want
to see the number of requests accepted but not yet being handled
(controlled by the <Connector>'s "acceptCount" attribute), the
number of
request processors (is this "thread pools" above?), the number of
connections total/available/used in JDBC connection pools.
Ah, that is interesting too: queue fill levels that should under
normal circumstances be more or less empty. Much like the
ObjectPendingFinalizationCount. Thanks for that.
How would I use it, though? In my Tomcat acceptCount has a value of
100. That's probaly an upper limit. What is the 'un-use' property that
goes with this upper limit?
What MBean can I talk to about JDBC connection pooling?
--
Kees Jan
http://java-monitor.com/forum/
[EMAIL PROTECTED]
06-51838192
Human beings make life so interesting. Do you know that in a universe
so full of wonders,
they have managed to invent boredom. Quite astonishing... -- Terry
Partchett
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