On 12/31/10 3:46 AM, Don Hill wrote: > Chris, > > Thanks for following up on this. From what I can tell it appears that the > HTTPD server is stalling at MaxClients.
How are you measuring connections and arriving at the above? The documentation for 2.0 states that MaxClients is configurable: http://httpd.apache.org/docs/2.0/mod/mpm_common.html#maxclients > This usually happens after some > mailing and the site gets hit really hard with users, upward of 3000 active > sessions being handle by 2 HTTPD servers and 4 Tomcat instances. What do you mean by 'sessions' and how are you counting them? HttpSessions in Tomcat, or something else? > Since we > are using prefork/mod_jk it seems there could also be some high CPU usage. Why prefork *or* mod_jk? Could be, or is high CPU usage? What is your average CPU usage per machine? And at peak load? > I > have done extensive profiling from a heap perspective using jstat and jmap. > I think I have the JVM tuned pretty good at this point. What are your JVM settings? > The Tomcat severs > also had maxthreads for each JVM set really high like 1000 on the AJP/1.3 > connector. I brought each JVM down to 200 max threads. What do you have in the mod_jk config for each worker? > Currently there are 2 VHOSTS on each machine with one HTTPD instance. We > are load balancing via a F5 Load balancer. The LB manages load accros all 4 > VHOST. Each VHOST uses one worker for to talk to one dedicated tomcat JVM. How does the F5 distinguish between vhosts, are they named differently? So there's 2 HTTPD with 2 vhosts and 4 Tomcats, is the below correct? LB --------------------- | | HTTPD HTTPD ----------- ----------- | | | | Tomcat Tomcat Tomcat Tomcat The Tomcat's have 200 threads each, so your max concurrent connections is 800. What led you to reduce the number of connections? p > Besides doing upgrades to Tomcat/HTTPD servers do you think there are any > configuration issues or can you suggest a better layout for this env. I was > thinking of getting rid of the vhosts and use a balancer config in the > mod_jk.config to manage the load to the Tomcat JVMs. This way the load could > be balanced based on the Tomcat usage and not the VHOST usage as some of the > load could be coming from static content and messing up the LB's balancing > ability. > > I was also thinking that we should switch to worker mpm instead of the > prefork. > > Anyways any thoughts or suggestions would be great. > > > > On Thu, Dec 30, 2010 at 8:19 PM, Christopher Schultz < > ch...@christopherschultz.net> wrote: > > Don, > > On 12/30/2010 10:41 AM, Don Hill wrote: >>>> My mistake, Here are the details. I should have confirmed first before >>>> posting but besides the apache version everything else is correct. >>>> >>>> tomcat 5.5.2.7 > > That's not a version published by Tomcat. More likely, this is a version > packaged by RHEL. If it's really based upon Tomcat 5.5.2 (a reasonable > guess), you seriously need to upgrade. If that was a typo and you are > really running Tomcat 5.5.27, then you could still afford to upgrade to > 5.5.31 which is the latest. > > You described your environment to a certain extent, but didn't say what > your goals were: are you experiencing any problems with your setup? Are > you just looking to streamline things so that you can increase load > without having to upgrade anything? > > If things are going well, why change anything? > > If you have a specific goal, let us know what it is and maybe we can > help you with it. > > -chris >> --------------------------------------------------------------------- To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org For additional commands, e-mail: users-h...@tomcat.apache.org >> >>
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