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From Kaleb Pederson <kpeder...@mail.ewu.edu>
Subject Re: Tomcat becoming almost completely non-responsive
Date Mon, 04 Oct 2004 14:21:15 GMT
On Friday 01 October 2004 4:29 pm, Kumar, Sunitha wrote:
> What command did you use to generate the thread dump?

I'm in Linux, so I used kill -QUIT <pid> where <pid> was the process ID.

--Kaleb

> -sunitha
>
> -----Original Message-----
> From: Kaleb Pederson [mailto:kpederson@mail.ewu.edu]
> Sent: Friday, October 01, 2004 3:08 PM
> To: Tomcat Users List
> Subject: Tomcat becoming almost completely non-responsive
>
>
> Hello,
>
> I have an interesting problem.  After a while, tomcat (5.0.27) becomes
> almost
> completely non-responsive.  If I telnet in to port 8009  (I'm using
> apache
> and mod_jk2), I get no response, at least not within the default
> timeout.  If
> a browse to a page, I will generally, after about 4-5 minutes, see a
> page
> returned.
>
> To narrow down the slowness, I generated a full thread dump, and found
> the
> following information:
>
> [ see attachment for more info]
> Total threads: 180
> executeQuery: 2 //  executing a db query
> validateConnection: 0 // trying to validate their connection
> validateObect: 48 // in
> commons.dbcp.PoolableConnectionFactory.validateObject
> socketAccept: 3 // accepting a socket
> socketRead0: 10 // reading a socket
> ReferenceQueue: 1
> ThreadPool$MonitorRunnable: 2
> borrowObject and Object.wait: 85 // trying to get an object from the
> pool
> Object.wait: 20 // threads just waiting around
> Remaining:  9 // misc. threads
>
> My database connection is setup so that I have 50 allowed connections,
> which
> matches my 48 in validateObject and 2 executing queries.  However, when
> I
> query the database status, I see 2 active threads and the rest are
> 'sleeping', just waiting around, as they would be if the connection pool
>
> hadn't released them yet.
>
> So, why would there be 48 connections that seemed locked and weren't
> querying
> the DB?  And then the other 85 that were seemingly waiting on the 45?
> Any
> ideas what might be going on?  The DB is ready?  I have log abandoned
> turned
> and an haven't seen a problem yet.  If the load drops sufficiently on
> the
> server, everything eventually returns back to normal, otherwise it takes
> 5-10
> minutes to get a response from the server.
>
> I have attached an abbreviated form of the thread dump which should
> provide
> all the critical information and can provide as much other information
> as is
> necessary.
>
> Thanks for the help.  *All* suggestions welcome ;)
>
> --Kaleb
>
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