dtrace discuss - Nov 2007 - dtrace on sun app server 9.1

I have an instance of sas 9.1 with connection pooling, oracle thin client. Under
load, the app server locks up. By that, I mean that no JSP can be run from that
point on, and I cant even access the web admin. I cant even do a proper shutdown
from asadmin stop-domain.

I do have connection pool leak detection and reclaim enabled (new to 9.1). But I
dont even reach the max connections that it''ll lock up, at which point
I am blind. I cant refer to the monitor since everything is locked.

So I figured this should be an ideal task for dtrace, right? except I''m
not sure where to start. This is java and all, whereas usually my dtracing is c
or c++ apps, and most of the time, I wrote them, so it helps. I''m a
little lost as to how the internals of SAS work, and how to use dtrace in that
context.

Anybody has done anything like that?

Francois
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Hi Francois,
>So I figured this should be an ideal task for dtrace, right? 
>except I''m not sure where to start. This is java and all, 
You can get started by listing couple of things:

1. What JVM are you using ? JDK 1.5, 1.6 ?

2. Based on no.1 try to build yourself certain procedures how can you
get started with DTrace for your debug:
 2.1 Use the DVM agent if you are using JDK 1.5
 2.2 Use the Hotspot provider found for Java 1.6
 2.3 If 2.2 applicable use DTraceToolkit and check the Java category

You can start by simple understanding how jstack() works. Check out the DTrace
user guide or one of DTT presentations:
http://www.opensolaris.org/os/community/dtrace/dtracetoolkit/

Cheers,
Stefan