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From Randy Layman <randy.lay...@aswethink.com>
Subject RE: AW: Java program interferring with Tomcat
Date Mon, 19 Nov 2001 18:45:35 GMT


> -----Original Message-----
> From: David Frankson [mailto:dfrankson@qwest.net]
> Sent: Monday, November 19, 2001 1:42 PM
> To: Tomcat Users List
> Subject: Re: AW: Java program interferring with Tomcat
> 
> 
>     Only Tomcat hangs, the other program continues on.  I 
> thought a database
> deadlock only happens when both threads are trying to write 
> and holding a
> lock on each other's data?  The external java process is read-only.

Not with SQL Server.  If thread A has a write lock on a table, thread b will
wait until the write is completed before reading.  If thread A is in a
transaction that is long running then a perfectly funcitoning application
can seem to hang.  Its also possible that some form of infinite loop or
deadlock in thread A could cause it to never release the transaction, making
you either kill the application or use Enterprise Manager to kill the lock.


> 
> How do you do a thread-dump on when you are running Tomcat as 
> a service on
> Win2k?
> 
> Dave
> 
> 
> ----- Original Message -----
> From: "Denis Haskin" <Denis@HaskinFerguson.net>
> To: "Tomcat Users List" <tomcat-user@jakarta.apache.org>;
> <dfrankson@qwest.net>
> Sent: Monday, November 19, 2001 12:09 PM
> Subject: Re: AW: Java program interferring with Tomcat
> 
> 
> > Ralph Einfeldt wrote:
> >
> > > Sounds like a deadlock on the database.
> > >
> > > To verify that have a look at the server manager
> > > to see if there are locks.
> >
> > I agree with Ralph, that the problem is probably in your SQL access.
> >
> > Do *both* processes hang (e.g. Tomcat & the scheduled job) or only
> > Tomcat?
> >
> > I would also look at a thread dump to see what thread is 
> locked & where.
> > Go to the window in which Tomcat is running and do a 
> Control-Break.  This
> > is usually easier if you've started Tomcat with "run", not "start".
> >
> > dwh
> >
> >
> > --
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> 
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