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From Andrew Pliszka <apliszka-pub...@alienforceit.com>
Subject Re: Performance tuning parameters
Date Fri, 16 Feb 2007 17:06:49 GMT
Hi,

Do you have any load balancer? I am sorry if this is a trivial 
questions, but I have worked with cases that people have no load 
balancer and connections are just killing them.

Now, if you do not have a load balancer you might consider NetScaler, it 
might lower your number of connections considerably.

Andrew Pliszka
j r wrote:

> I am gleaning from your comments that MaxThreads is the only thing to
> tweak.  Yes I do really have a connection issue.  I have millions and
> millions of connection requests on a very small pool of servers.  The app
> has been tuned constantly over years.  I am either bound to buy more 
> servers
> or tweak tomcat to get more throughput.  In reality, I probably need 
> to do
> both.
>
> On a large pageview day, we will overflow the 750 MaxThreads.  This is
> noticed by the MaxThreads limit being exceeded error message.  We have
> tweaked all pieces of the tomcat config.  I was hoping a post here 
> could get
> more explanation of the parameters.  We have our experience to fall 
> back on,
> but I was hoping for more.
>
> If MaxThreads is the main thing to tweak, we will continue doing so.  
> There
> is a limit to this though.  You should create the funnel for customer
> requests (webserver limits, mod_jk limits, and tomcat limits).  Exploding
> MaxThreads to a large number just to be large does not seem to fit with
> having an acceptCount value or the funnel that should be created.
>
>
> Thanks,
> J
>
> On 2/16/07, Andrew Miehs <andrew@2sheds.de> wrote:
>
>>
>> -----BEGIN PGP SIGNED MESSAGE-----
>> Hash: SHA1
>>
>> Dear J,
>>
>> The focus should be on your application, and configuring everything
>> thing around that.
>>
>> If you REALLY have an out of  connection problem, increase Max
>> Threads to 10000, but I don't
>> think that will really help you. The problem is usually that each
>> individual request takes
>> tooo long, which again, points back to your application - There isn't
>> that much to tweak
>> in tomcat. Once you have configured your application, then you can
>> start looking at the
>> kernel - but these only bring small % improvements.
>>
>> Without more information - ie: current number of threads being used,
>> it is very
>> hard to answer your question.
>>
>> Cheers
>>
>> Andrew
>>
>> On 16/02/2007, at 4:43 AM, j r wrote:
>>
>> > The focus should be on the tomcat tweaking.  We get errors in the
>> > tomcat
>> > error logs that say tomcat has reached its connection limits.  I
>> > never said
>> > that it was serving slow.  It hits connection limits which means
>> > that the
>> > app will not serve any more traffic until connections clear.
>> >
>> > If a box definitely has more capacity (dual core, dual procs), then
>> > my best
>> > guess is that tomcat is not tuned perfectly to allow the max amount of
>> > connections in.  We have raised MaxThreads in the past to allow more
>> > connections in.  This works, but surely other knobs are important
>> > to be
>> > tweaked.
>> >
>> > I am looking for good definitions and/or best practices on which
>> > knobs to
>> > tweak to allow the max connections in before exhausting the jvm native
>> > memory allocation or cpu on the box.
>> >
>> >
>> >
>> > Thanks,
>> > J
>> >
>> > On 2/15/07, Andrew Miehs <andrew@2sheds.de> wrote:
>> >>
>> >> -----BEGIN PGP SIGNED MESSAGE-----
>> >> Hash: SHA1
>> >>
>> >> Dear J'
>> >>
>> >> What do you mean you are hitting connection limits?! Are you getting
>> >> errors? What are you seeing that makes you think that is slow?
>> >> Is there a database involved in this application?
>> >>
>> >> I assume you are running linux on your server, with a 2.6 kernel.
>> >>
>> >> run the following commands while your box
>> >>
>> >> 1)  ps auxH
>> >> 2)  ps auxH |grep -c java
>> >> 3)  vmstat 5 5
>> >> 4)  iostat 5 3
>> >>
>> >> Then we will have a bit of an idea what is going on.
>> >>
>> >> Andrew
>> >>
>> >>
>> >>
>> >>
>> >> On 15/02/2007, at 9:36 PM, j r wrote:
>> >>
>> >> > The reason it is hitting its limits is easy: traffic.  We easily
>> >> > get enough
>> >> > website traffic to overflow the connection limits unless I have
>> >> > many boxes
>> >> > available to serve.  I know these can be configured to handle more
>> >> > connections.  I know that we should be able to do this in the
>> >> tomcat
>> >> > server.  That is why I need those tweaking parameters defined.
>> >> >
>> >> >
>> >> >
>> >> > Thanks,
>> >> > j
>> >> >
>> >> > On 2/15/07, Leon Rosenberg <rosenberg.leon@googlemail.com> wrote:
>> >> >>
>> >> >> First you should investigate why tomcat is hitting its limits.
>> >> >> Why do you think it does? Which resource is the limit?
>> >> >> Do you have/use any monitoring software? moskito? lambdaprobe?
>> >> >> tomcat-manager?
>> >> >>
>> >> >> regards
>> >> >> Leon
>> >> >>
>> >> >> On 2/15/07, j r <jreynolds11@gmail.com> wrote:
>> >> >> > I have searched for exact documentation on this, and I always
>> >> find
>> >> >> > conflicting info.  Therefore I am reaching out to this list.
 I
>> >> >> have the
>> >> >> > following info and questions:
>> >> >> >
>> >> >> > - we are running tomcat 5.5.20
>> >> >> > - we have the following configs in server.xml:
>> >> >> >            <Connector port="8009"
>> >> >> >                enableLookups="false" redirectPort="8443"
>> >> debug="0"
>> >> >> >                maxThreads="750" minSpareThreads="100"
>> >> >> maxSpareThreads="250"
>> >> >> >                acceptCount="100" connectionTimeout="5000"
>> >> >> > tomcatAuthentication="
>> >> >> >                false"
>> >> >> >
>> >> >> > - we have extra capacity (mem, cpu, etc.) on the servers,
yet
>> >> >> tomcat is
>> >> >> > hitting connection limits
>> >> >> > - we feel that tomcat can serve more, so what do we tune to
make
>> >> >> it do
>> >> >> so?
>> >> >> >     - maxThreads?
>> >> >> >     - minSpareThreads?
>> >> >> >     - maxSpareThreads?
>> >> >> >     - acceptCount?
>> >> >> >
>> >> >> >
>> >> >> > Honestly, I would rather love an exact definition of what
each
>> >> >> of those
>> >> >> > would do to the tomcat server if tweaked.  Knowing that would
be
>> >> >> nirvana
>> >> >> for
>> >> >> > tuning.
>> >> >> >
>> >> >> >
>> >> >> >
>> >> >> > -j
>> >> >> >
>> >> >>
>> >> >>
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>> >> >>
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>



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