I have a Tomcat based site, that receives about 4000 requests a day.
It is a low memory server with only 350MB of ram.  But I would think
that that even Tomcat should be able to handle that.  Anyway, I keep
getting out of memory errors and the JVM will normally quit after it
reaches a certain threshold.  I want to post this and see if it rings
a bell with anyone.  I am currently using LambdaProbe(tomcat probe) to
collect memory utilization, memory statistics.

Application itself.
Spring2, Hibernate3, MySQL5 based application.
Java(TM) 2 Runtime Environment, Standard Edition  1.5.0_08-b03  Java
HotSpot(TM) Server VM)
Linux (unknown) i386 2.6.9-023stab043.1-enterprise
Apache Tomcat/5.5.20

Here are some memory stats from Lambda Probe.  These are stats while
the application is running.  I am assuming relative to the heap? as
opposed to the system memory.

Current memory usage is     42.8%
Free: 89.51 MB Total: 197.94 MB Max: 253.19 MB

Name Usage score Plot Used Committed Maximum Initial Group
 Survivor Space       1.09Mb  2.19Mb  2.81Mb  2.19Mb  HEAP
 Perm Gen       45.98Mb  46.00Mb  64.00Mb  16.00Mb  NON_HEAP
 Tenured Gen       106.23Mb  177.81Mb  227.56Mb  177.81Mb  HEAP
 Eden Space       12.61Mb  17.94Mb  22.81Mb  17.81Mb  HEAP
 Code Cache       10.17Mb  10.19Mb  48.00Mb  2.25Mb  NON_HEAP
 Total       176.09Mb  254.13Mb  365.19Mb  216.06Mb  TOTAL

I am also assuming that when the "Free" memory reaches 0, that the JVM
will crash.  I can't tell because the probe application is running
inside of that jvm.

Here is an error from the logs when the jvm stops.

Key line = "JVM exited unexpectedly while stopping the application."

INFO   | jvm 1    | 2007/10/12 14:23:22 | 2007-10-12 14:23:22,183 INFO
[org.spirit.spring.BotListRubyController] - <BotListRubyController:
showForm() uri=/botlist/spring/botverse/linkaddcomment.html>
INFO   | jvm 1    | 2007/10/12 14:23:22 | 2007-10-12 14:23:22,183 INFO
[org.spirit.spring.BotListRubyController] - <BotListRubyController:
getDefaultViewNameFromRequest() - From Request:
http://www.botspiritcompany.com/botlist/spring/botverse/linkaddcomment.html>
ERROR  | wrapper  | 2007/10/12 14:23:26 | JVM exited unexpectedly
while stopping the application.
STATUS | wrapper  | 2007/10/12 14:23:26 | <-- Wrapper Stopped

STATUS | wrapper  | 2007/10/12 15:05:03 | --> Wrapper Started as
Daemon
STATUS | wrapper  | 2007/10/12 15:05:03 | Launching a JVM...

Berlin Brown