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From "Bill Barker" <wbar...@wilshire.com>
Subject Re: DO NOT REPLY [Bug 16001] - Tag.release() not invoked
Date Sat, 18 Jan 2003 03:58:27 GMT

----- Original Message -----
From: "Glenn Nielsen" <glenn@mail.more.net>
To: "Tomcat Developers List" <tomcat-dev@jakarta.apache.org>
Sent: Friday, January 17, 2003 7:04 PM
Subject: Re: DO NOT REPLY [Bug 16001] - Tag.release() not invoked


> Costin Manolache wrote:
> > Hans Bergsten wrote:
> >
> >
> >>evaluation all in one place. To make things even easier, these tag
> >>handlers can _not_ be reused at all. Benchmarks with modern JVMs show
> >>that the gain from reuse is not worth all the trouble. So, for new
> >>tags we recommend using the SimpleTag API which takes care of the
> >>problem by forbidding reuse.
> >
> >
> > Wow. I would be _very_ curious to see those benchmarks and the "modern"
> > JVM that was used.
> >
> > All my tests ( including JDK1.4, IBM vms, GCJ ) show that reusing is
well
> > worth the trouble - at least if you have 100s of requests per second
> > ( it is not worht the trouble for very low loads ). But I'm happy to
> > hear that I'm wrong.
> >
> > Costin
>
> Hear, Hear!!
>
> I saw a significant, measureable improvement in performance when I
upgraded
> our production systems to Jasper 2 with tag pooling from Jasper 1 without.
> CPU load on the production server dropped around 30%, request latency was
> reduced significantly, etc.  The app server handles 30k-100K requests per
day.
> This is on a Sun dual CPU E250, 768MB of Ram, that is run solely as an app
server.
> OS is Solaris 8, JVM is 1.3.1 using HotSpot server, and I have spent time
tuning
> the JVM stack and GC java startup args.
>
> Tag pooling elminates significant amounts of GC.  That is where the real
> benefit of tag pooling comes from.  With tag pooing the frequency and
> length of GC's are reduced a great deal.
>

I saw just the opposite.  Jasper2 with tag-pooling was a real dog (the time
spent in synchronized methods to maintain the pool completely swamped any
benefit from GC).  After patching my copy to make don't-tag-pool the default
(since there isn't any way to do this in the config :( ), then Tomcat
4.1/Jasper2 was about 60% faster that Tomcat 3.3/Jasper1 when I 'ab'
benchmarked it against one of my more complex pages.

> Glenn
>
>
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