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List:       tomcat-user
Subject:    RE: Tomcat 5.5.25 freezes
From:       "Surendrakumar Viswanathan -X (suviswan - HCL at Cisco)" <suviswan () cisco ! com>
Date:       2008-06-30 8:51:27
Message-ID: 7906EBB854491A438474875D1D737321053E1BA5 () xmb-blr-418 ! apac ! cisco ! com
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Also make sure  GC is not an issue. If the occurrence is random and
there is no lock in threads / database , then GC is usually the cause.
You can enable JMX and monitor it using Jconsole. 

Cheers
Suren

> -----Original Message-----
> From: Peter Crowther [mailto:Peter.Crowther@melandra.com] 
> Sent: Monday, June 30, 2008 1:53 PM
> To: 'Tomcat Users List'
> Subject: RE: Tomcat 5.5.25 freezes
> 
> > From: Anthony Chamas [mailto:chamaster@gmail.com] I am 
> having quite a 
> > weird situation on a production server : tomcat seems to be stuck 
> > somewhere when handling http requests.
> > The activity being slow (10 users), some requests take exactly 30 
> > minutes to be processed.
> >
> > I have put aside the following :
> > -it happens on any page (not linked to a particular path)
> 
> Does it happen on plain content pages as well as dynamic 
> pages (for example, does a CSS ever wait 30 minutes to get 
> served)?  Only on dynamic pages, whether or not they touch 
> the database?  Only on dynamic pages that touch the database?
> 
> > -database lock : when that happens, I do not see any lock in the 
> > database.
> > -filters : we tried to deactivate all of them : same result 
> -I see no 
> > errors, warning or something significant in the log files.
> 
> Next debug step: When it occurs, get a thread dump of your 
> production server.  The way to do this varies by OS (which 
> you didn't tell us).  It's a non-destructive operation; it 
> will not cause your production server to halt, but it will 
> give you a trace of where each thread is in the system.  You 
> might want to do that twice, a few minutes apart, if you 
> reckon something's waiting 30 minutes.
> 
> That'll give you a lot of data to look over.  I'd be hunting 
> for threads that were waiting on locks or waiting in the 
> database connector.  Expect lots of waiting threads - most of 
> them will be idle, waiting to process a request.  This is not 
> an error condition, it's normal!
> 
> If you don't get any joy looking at the thread dump (and 
> they're not the easiest things in the world to interpret), 
> some of the folks on-list may be willing to help.
> 
>                 - Peter
> 
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