[Wrapper-user] Wrapper restarts GC'ing JVM - why?

[Christian B. <chr...@be...>]

Hi. While overall i am very pleased with the functionality and stability
of the Wrapper, i just cannot seem to figure out one problem. I went
through the docs and the mailing list archives, yet no idea. So here
goes:

The basic problem is that the Wrapper will restart my application if it
takes too long to garbage collect (this is as per observation). Consider
the following Wrapper log:

INFO   | jvm 1    | 2002/10/14 13:43:49 | Memory Status: 112 MB Used,
127 MB Total
INFO   | jvm 1    | 2002/10/14 13:43:56 | [Full GC
ERROR  | wrapper  | 2002/10/14 13:46:02 | JVM appears hung: Timed out
waiting for signal from JVM.
ERROR  | wrapper  | 2002/10/14 13:46:02 | Java Virtual Machine did not
exit on request, terminated
STATUS | wrapper  | 2002/10/14 13:46:08 | Launching a JVM...

As can be seen, i am hitting the heap limit, at which point a full GC
kicks in (JVM running in verbose mode). The machine the JVM is running
on is short on main memory and hits the page file at this point,
swapping for about two minutes (see timestamps) - finally, the Wrapper
decides it's dead and restarts it.

While i don't want to argue the fact the 2 minute GCs are pretty bad ;)
- i still think the Wrapper should not have restarted the JVM. I have
gone through most of the docs and tuned some of the advanced parameters,
namely:

wrapper.ping.timeout=120

From my understanding, this will make the Wrapper wait for 120 seconds
if no pings get answered from the JVM, then decide it's dead. From the
above log, it looks like this timeout is working (death comes after some
2 minutes). Now i did look into the 

wrapper.cpu.timeout=10

parameter and left it at the default. my understanding is, that once the
wrapper detects that either itself or the JVM is stalled, then the ping
timeout is extended. from the docs, it looks like this functionality is
there to address the problem i am describing above. however, in my case,
it looks like the decision to restart is made before the stalled process
detection kicks in - is this a bug or the expected behaviour? 

I'd appreciate any help in figuring this out. Oh, and i've seen this on
(underpowerd) Windows and Solaris boxen.


thanks,


chr.