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From Peter Lin <wool...@gmail.com>
Subject Re: JVM memory size changing dramatically
Date Wed, 28 Jul 2004 16:40:31 GMT
keep in mind that even if you set the max connections to 300, it
doesn't mean it can realiably handle 300 concurrent queries with good
performance. I would use JMeter to stress test the database with real
queries.

Once you get a picture of how the queries scale in relation to the
number of concurrent queries, you'll have a much better idea of the
scalability of the application. It's a bit erroneous to think of
scalability in terms of Tomcat5.  In my biased opinion all of the
major webservers are roughly equal today.

the difference really comes down to how you write your application.
Assuming you've take time to tune your sql queries and create the
proper indexes on the tables, your queries should take 200-400ms. On a
dual CPU box, a respectable throughput would be 10-20 queries per
second. The chances of double or tripling that throughput on the same
hardware is a matter of optimizing your database tables and
denormalizing the database schema for performance. Realistically, you
won't be able to handle 500 concurrent requests to the webserver
without some sort of in memory cache.  Without caching, no webserver
will be able to handle 500 concurrent requests. I hope that helps

peter



On Wed, 28 Jul 2004 19:31:20 +0200, Futchi <msafadi@massar.com> wrote:
> 
> 
> I don't think it's related to the IIS5, my web server is Tomcat5. how
> many concurrent requests related to my hardware (JVM) and tomcat
> threading.
> 
> I have MySql server 4.0.16 (max_connections=300), and Tomcat5 both
> running on the same machine.
> 
> 
> 
> 
> -----Original Message-----
> From: Peter Lin [mailto:woolfel@gmail.com]
> Sent: Wednesday, July 28, 2004 17:53
> To: Tomcat Users List
> Subject: Re: JVM memory size changing dramatically
> 
> as others have stated, the only way to know is to stress test your
> app. even without running a test, I can tell you IIS5 running on a
> dual CPU box cannot handle 500 concurrent requests for dynamic pages.
> 
> 500 concurrent requests for static files isn't a problem.
> 
> Depending on the kind of application, the maximum concurrent requests
> maybe as low as a dozen or as high as 50-60. Does your app make
> database queries? How long do the queries take?  How many CPU's does
> the database server have? Which version of Sql Server do you run? Is
> the database hosted on a separate box? What kind of router are you
> using between the webserver and database? Is there a dedicated
> ethernet port and router between the two tiers?
> 
> These are all important questions to ask and answer. Once you answer
> most of these questions, you'll be able to confidently say what your
> webapp can handle. good luck
> 
> peter
> 
> On Wed, 28 Jul 2004 16:43:29 +0100, Dale, Matt <matt.dale@becogent.com>
> wrote:
> >
> > Only you can answer these questions by testing your application with
> something like Jmeter. Devise tests that replicate user behaviour and
> increase the load until it breaks. Then you will be able to see what it
> can handle and how windows copes with the load.
> >
> > Ta
> > Matt
> >
> >
> >
> > -----Original Message-----
> > From: Safadi, Mazin [mailto:msafadi@massar.com]
> > Sent: 28 July 2004 17:40
> > To: 'Tomcat Users List'
> > Subject: RE: JVM memory size changing dramatically
> >
> > But windows has enough space, 2GB memory, Dual processors, this app.
> is
> > running but still Tomcat does not receive hits, what will happen if
> the
> > server has up to 500 visitors concurrently,
> > How windows will handle this?
> > How to make sure that JVM will not goes down?
> >
> > -----Original Message-----
> > From: Shapira, Yoav [mailto:Yoav.Shapira@mpi.com]
> > Sent: Wednesday, July 28, 2004 17:19
> > To: Tomcat Users List; msafadi@massar.com
> > Subject: RE: JVM memory size changing dramatically
> >
> > Hi,
> > Windows needs additional space for other things (including possibly
> idle
> > thread cleanup) and swaps your process into a paging area temporarily.
> > It's fairly standard practice, and as you noted results in no errors,
> so
> > don't worry about it.
> >
> > Yoav Shapira
> > Millennium Research Informatics
> >
> > >-----Original Message-----
> > >From: Futchi [mailto:msafadi@massar.com]
> > >Sent: Wednesday, July 28, 2004 12:11 PM
> > >To: Tomcat Users List
> > >Subject: JVM memory size changing dramatically
> > >
> > >Hi all,
> > >            I am running tomcat 5 on Win2003 server, my single app.
> has
> > >several threads running in the background (threads loading and
> writing
> > >data, detecting URL connections).
> > >
> > >Tomcat starting-up with 80 up 90 MB memory size as Win2003 shows in
> the
> > >Tasks Manager, it keeps running stable and getting up and down
> between
> > >80 and 93 MB memory size. After several hours, memory size gets down
> to
> > >5 MB very fast, and then start goes up to 90 MB also fast.   This
> > change
> > >happening in about 2-3 minutes only, then it becomes stable again
> > >jumping between 80-93 MB memory size.
> > >
> > >While this happening Tomcat is up and running, also my App. is up and
> > >running. I do not have any memory error messages.
> > >
> > >
> > >I doubt it is the GC, Anybody can explain that?!!!
> > >
> > >
> > >My JAVA_OPTS as follows
> > >
> > >
> > >JAVA_OPTS=-server -Xms256m -Xmx768m -XX:NewSize=64m
> -XX:MaxNewSize=64m
> > >-XX:SurvivorRatio=8 -XX:MaxTenuringThreshold=5
> > >-XX:TargetSurvivorRatio=75 -XX:PermSize=32m -XX:MaxPermSize=32m
> > -Xss128k
> > >-XX:+DisableExplicitGC
> > >
> > >
> >
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> >
> >
> >
> 
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