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From John Turner <tomcat-u...@johnturner.com>
Subject Re: Need help with performance issue - Tomcat 4.1.X
Date Fri, 11 Jul 2003 20:13:13 GMT

I'm certainly no guru, but if you are setting a max of 256 and then your 
app is soaking up 327 with no load whatsoever, I'd say you have a problem.  
Have you tried a max of 512?

John

On Fri, 11 Jul 2003 20:08:10 +0000, <tomcat-question@comcast.net> wrote:

> We are currently starting up with -Xmx256M.  Java is currently using 
> about 327MB and has been that way for hours.  I haven't really seen any 
> fluxuations at all, which leans me away from the garbage collection 
> issue.
>
> I created a hello.jsp, which is completely separate from our application. 
> Same results.  It takes about 30 seconds to return.
>
> In the hello.jsp, the results of the page return instantly to the 
> browser, but then it's as if tomcat just won't close the connection to 
> the browser.  The page is there, fully rendered, but just sits there 
> waiting for the server to tell it it is done.  Is there some way that the 
> tomcat connections could be failing to terminate properly?
>
>
> Our current maxProcessors = 75
> acceptCount = 10 (which is probably low but right now we have only a 
> couple users on the system).
>
> We're not using 1.4 so those options are out.
>
> -- Dave
>> Could be a Memory Leak/Garbage Collection issue (we had a similar 
>> problem with a memory intensive app),
>> maybe your heap is too small and java is running many Full GC's.
>> Start java with -verbose:gc and look in tomcat/logs/catalina.out for 
>> Garbage Collections.
>> (set Environment Variables JAVA_OPTS or CATALINA_OPTS in bin/catalina.sh 
>> to do this in Tomcat)
>>
>> ================================
>>
>> Try using a bigger Heapsize (though if you've got a Memory Leak that 
>> will only delay your problem)
>> or set initial Heapsize to same as maximum, for example 128MB:
>> -Xmx128m -Xms128m
>>
>> ================================
>>
>> Modify the Connector you are using to access Tomcat (in 
>> tomcat/conf/server.xml) and
>> try using more Tomcat Processors (maxProcessors=XX) or a bigger accept 
>> queue length (acceptCount=XX)
>> (test value for acceptCount: at least > concurrent users x 3)
>>
>> ================================
>>
>> Try using another method of garbage collection,
>> if you're using JDK 1.4.1 i'd try either
>>
>
>> ConcurrentGC with ParNewGC (ParNewGC on Multi-CPU machines):
>> -XX:+UseConcMarkSweepGC -XX:+UseParNewGC
>>
>> or ParallelGC with AdaptiveSizePolicy (saves you the work of Java Heap 
>> usage analyzing :-) :
>> -XX:UseParallelGC -XX:+UseAdaptiveSizePolicy
>>
>> A good article on GC can be found here: 
>> http://wireless.java.sun.com/midp/articles/garbagecollection2/
>>
>> ================================
>>
>>
>> At 18:04 11.07.2003 +0000, you wrote:
>> >With Tomcat 4.1.x
>> >
>> >We've recently run into an issue where some of our pages either
>> >a) take a really long time to come up (20+ seconds)   or
>> >b) come up, but never really finish loading (the status bar in IE shows 
>> >the the
>> >response hasn't finished).
>> >
>> >These are very simple pages (for example, a login page) and our server 
>> >load is
>> >minimal (maybe 10 concurrent users).  Then, mysteriously, the problem 
>> will go
>> >away by itself.  It will also return.
>> >
>> >Given the information above, I'm not expecting any solutions, but I 
>> could use
>
>> >some help steering me in the right direction with things to check.  
>> We're
>> >hooking up monitoring on the systems (Linux) to examine memory and CPU
>> >utilization during the slowdowns.
>> >
>> >Any things in particular we should be examining to try to find the 
>> problem?
>> >Any idea why the pages would never fully return from the server?
>> >
>> >TIA
>> >
>> >-- Dave
>> >
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>
>
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