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From Jeffrey Janner <Jeffrey.Jan...@PolyDyne.com>
Subject RE: Tomcat thread dump analysis
Date Thu, 09 May 2013 15:22:40 GMT
> -----Original Message-----
> From: Charles Richard [mailto:charles.r@thelearningbar.com]
> Sent: Thursday, May 09, 2013 7:03 AM
> To: Tomcat Users List
> Subject: Re: Tomcat thread dump analysis
> 
> On Wed, May 8, 2013 at 6:16 PM, Christopher Schultz <
> chris@christopherschultz.net> wrote:
> 
> > -----BEGIN PGP SIGNED MESSAGE-----
> > Hash: SHA256
> >
> > Charles,
> >
> > On 5/8/13 1:57 PM, Charles Richard wrote:
> > > I appreciate the friendly feedback! How do I show a lock? I don't
> > > see any threads that have a "BLOCKED" status. I do get this when I
> > > do a grep:
> > >
> > > [root@web01 stacks]# grep locked tomcat1_20130507_14\:38.stack | wc
> > > -l 154
> > >
> > > My connection pool is 150 and I do see 150 locks in the following
> > > type scenario which has a "locked":
> > >
> > > "TP-Processor416" daemon prio=10 tid=0x00002aff2939a800 nid=0x5ae7
> > > in Object.wait() [0x00002aff632ae000] java.lang.Thread.State:
> > > WAITING (on object monitor) at java.lang.Object.wait(Native
> > > Method) - waiting on <0x00002afe240fbc58> (a
> > > com.mchange.v2.resourcepool.BasicResourcePool)
> >
> > This only tells you the identity of the object monitor (the "lock").
> > What you are missing is the identities of the object monitors already
> > held by this and other threads. I believe your thread dump does not
> > include any of these.
> >
> > IIRC, the Oracle JVM can (when prodded) produce a thread dump which
> > includes deadlock detection and will show the suspected-deadlocked
> > threads, the held lock ids and what threads are waiting on.
> >
> > Perhaps you can get a "better" thread dump via other means? How did
> > you get the one you have now?
> >
> > - -chris
> >
> 
> I got the current dump by using jstack which is in my 1.6.0_22 jdk
> binaries. How should i produce this stack? What would a dump showing a
> suspected-deadlocked threads look like?
> 
> Thanks!
> 
> Cheers,
> Charles

I find jconsole infinitely useful for tracing deadlocks.
It's also available in the jdk binaries.  And the tomcat docs have setup instructions.
Jeff


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