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From Peter Lin <>
Subject Re: scaling Tomcat
Date Wed, 17 Apr 2002 01:45:51 GMT

I've been fortunate enough to have some experience in
building "enterprise" systems. Depending on who you
ask, "enterprise" means a different thing. In my
particular case, the site had to be able to support a
half million users. Not all at once mind you, but
support the equivalent traffic if there were a half
million paying subscribers.

If I use your numbers, here are some possible ways to
analyze and guess what such a system might need.

--- Saddest OfAllKeys <> wrote:
> hello,
> My apologies if these are FAQs. I've searched for
> them.
> I'm working on a webapp.  My team wants to measure
> performance/scale from the get-go.  The plan is to
> start with Apache/Tomcat and measure, using
> commercial
> products only when necessary.  An approximate goal
> is
> 500 users of the course of a day, with a response
> time
> of 3-5 seconds.

Since it's a portal like site, I'll use yahoo and Cnet
as a base of comparison. I tend to visit yahoo about
10 times a day and each time I probably view about 3-5
pages. Even though these numbers may not apply to your
particular case, it should give you an idea of how to
go about calculating the theoritical peak traffic.

10 visits X 5 page views = 50 hits

If I assume 50 hits a day per subscriber as average,
than the total number of hits the system has to
support per day is

50 X 500 = 25000 hits

Of course that number should be tripled to take into
account traffic spikes, but lets just say 100K hits a
day. That amount of traffic isn't alot my portal
standards. In fact, it's pretty darn low, so unless
your connection to the database is really slow, or
doesn't use connection pooling, I wouldn't worry about
performance. Of course, that assuming you're only
grabbing small chunks of data and not huge blobs that
are multiple megs.

In terms of tweaking tomcat, there are two ways.

1. increase the number of processors in server.xml
2. increase the heap settings

Beyond that, it's hard to say how to scale
tomcat/apache, since how you implement the portal has
the biggest impact on how it scales.

> Q1: Can someone point me to info on tweaking Apache
> and Tomcat for performance/scale? I have James
> Goodwill's Tomcat book and while it is good, it
> doesn't address this issue.
> Q2: Are there any rules of thumb for the high-end of
> Tomcat's ability re: number of users?  I know this
> is
> terribly vague.  FWIW, the webapp is a portal server
> and not really dealing with EJB.  It queries some
> remote databases via HTTP and other protocols.
> Any advice/comments are greatly appreciated.
> thanks,
> Mike

You can search the archives for the benchmarks I
posted on tomcat with coyote and httpconnector.

hope that helps.


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