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From "Marc Saegesser" <marc.saeges...@apropos.com>
Subject RE: 3.2.2b3 mod_jk gets stuck in readFully
Date Mon, 23 Apr 2001 00:23:24 GMT
I encountered the hang problems using Apache 1.3.9.

I don't know of any hard-coded array sizes that impact thread pooling in
3.2.2 and if there are any they are bugs and should be fixed.

> -----Original Message-----
> From: Rainer Jung [mailto:rainer.jung@kippdata.de]
> Sent: Sunday, April 22, 2001 1:30 PM
> To: tomcat-dev@jakarta.apache.org
> Subject: RE: 3.2.2b3 mod_jk gets stuck in readFully
>
>
> If 100 is a constraint for the pool size, it should be stated in
> the Tomcat
> User's manual, since there it is explained how to increase the
> pool, but no
> max is given.
>
> I observed Exceptions when using more than 100 threads in the
> pool, coming
> from one or two arrays which have fixed size 100 in the tomcat code.
>
> I could not reproduce these errors after I updated from 3.2 to
> 3.2.2 and to
> 3.3. Is there a reason, why I could stably use a bigger pool with these
> version? I put 240 concurrent requests on apache.
>
> Which was the apache version you used, when the hang problem occured?
>
> At 16:47 22.04.01 , you wrote:
> >Two things.  First, the other problem that I was seeing turned
> out to be an
> >Apache problem.  I switched to Apache 1.3.19 and my thread hang problems
> >went away.  That problem seemed to be a synchronization thing
> that occurred
> >if requests showed up too close together.
> >
> >As for the thread pool stuff.  By default, Tomcat 3.2.x thread
> pools create
> >10 threads.  This can be changed using the min_spare_threads
> parameter.  The
> >pools will grow as needed up to the maximum number of threads
> allowed (100,
> >by default).  You can increase the maximum number of allowed
> threads using
> >the max_threads parameter.  See if this fixes your problem
> better than using
> >SimpleTcpConnector.
> >
> >
> > > -----Original Message-----
> > > From: Pogo Com [mailto:pogo_tomcat@yahoo.com]
> > > Sent: Saturday, April 21, 2001 5:39 PM
> > > To: Marc Saegesser; tomcat-dev@jakarta.apache.org
> > > Subject: RE: 3.2.2b3 mod_jk gets stuck in readFully
> > >
> > >
> > > After quite a bit of struggle, I think I found out what is
> going on.  The
> > > problem is that the default configuration of Tomcat does not
> have enough
> > > threads in its thread pool for the default configuration of
> Apache.  This
> > > issue would only be apparent if many Apache children were in use.
> > >
> > > The result was that any Apache children over the number of
> Tomcat threads
> > > would hang waiting for Tomcat to respond to requests.  Tomcat
> would not
> > > respond until threads became available, which could be quite a
> > > long time if
> > > Apache children were not dying off (ie, because load was
> > > increasing during the
> > > day).
> > >
> > > I was wrong about the threads being stuck in readFully.  The real
> > > problem is
> > > that not enough threads existed at all (ie, the thread handling
> > > socket accept
> > > would be blocked).
> > >
> > > The simplest workaround is to change the AJP13 connector to
> > > SimpleTcpConnector
> > > rather than PoolTcpConnector in server.xml.
> > >
> > > I strongly suggest that thread pool exhaustion emit a log
> > > message, since this
> > > was quite difficult to track down.  Additionally, it would be
> > > better for the
> > > default configuration to be more robust.
> > >
> > > Bill
> > >
> > >
> > >
> > > --- Marc Saegesser <marc.saegesser@apropos.com> wrote:
> > > > I finally got some time to look at this and I think I can
> duplicate the
> > > > problem your seeing.  Hopefully, its the problem your
> seeing, or else we
> > > > have two serious problems.
> > >
> > >
> > > __________________________________________________
> > > Do You Yahoo!?
> > > Yahoo! Auctions - buy the things you want at great prices
> > > http://auctions.yahoo.com/


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