On Aug 13, 2013, at 11:37 AM, "Smith, Mitchell" <mitchell.sm...@cwc.com> wrote:
> Dan, > > I am currently developing/testing with the latest version: 7.0.42 Excellent! > *Note this is different than the configuration you specified above, which > appears like it's trying to restrict the number of sessions that the > manager will create* > Yes, maxActiveSessions is the parameter I am using. As I know the memory > footprint of a session in the application I have set the parameter to the > number of sessions I would support per application instance. Thus ensuring > that an instance is not overloaded by sessions. Since sessions are your limiting factor, you might want to look at using mod_jk. It has a couple load balancing algorithms based on session count, which might make this easier for you. See the "method" directive here. http://tomcat.apache.org/connectors-doc/reference/workers.html > My idea is based on the understanding that I have a fixed user base, and my > infrastructure is designed to scale for this user base. The issue occurs if > the LB fails to balance (for what ever reason), the tomcat instance could > block new sessions and pass the user to a static (helpful) error page > and/or redirect them back to the base URL of the LB. You should probably look at what is going on with your load balancer. If a request fails, the load balancer should notice and temporarily take the Tomcat instance out of the load balancing group. Are you using mod_proxy or mod_jk? Can you share your load balancer configuration? > What I am struggling is the ability to catch the IllegalStateException that > would be thrown by the Manager, and forward to the error/redirect as a > result of this. How are you trying to catch this? In the application? With a filter? Dan > > > > On 13 August 2013 15:18, Daniel Mikusa <dmik...@gopivotal.com> wrote: > >> On Aug 13, 2013, at 9:33 AM, "Smith, Mitchell" <mitchell.sm...@cwc.com> >> wrote: >> >>> On 13 August 2013 13:24, Daniel Mikusa <dmik...@gopivotal.com> wrote: >>> >>>> On Aug 13, 2013, at 6:43 AM, "Smith, Mitchell" <mitchell.sm...@cwc.com> >>>> wrote: >>>> >>>>> Hi, >>>>> >>>> >>>> What version of Tomcat are you using? 6.0.x or 7.0.x? >>>> >>> Tomcat7 >> >> Please include the complete version number. There are 42 different Tomcat >> 7 releases. The more specific you can be the better response you'll get >> from the list. >> >>> >>>> >>>>> I was looking at using the maxActiveConnections in the application >>>> context, >>>> >>>> Please include the relevant configuration from your server.xml or >>>> context.xml file. >>>> >>> Context.xml >>> >>>> <Context> >>>> >>>> <!-- Default set of monitored resources --> >>>> >>>> <WatchedResource>WEB-INF/web.xml</WatchedResource> >>>> >>>> <!-- Uncomment this to disable session persistence across Tomcat >>>> restarts --> >>>> >>>> <Manager pathname="" >>>> *maxActiveConnections="150" >> >> Are you referring to "maxActiveSessions"? >> >> https://tomcat.apache.org/tomcat-7.0-doc/config/manager.html >> >>>> */> >>>> <!-- Uncomment this to enable Comet connection tacking (provides >> events >>>> on session expiration as well as webapp lifecycle) --> >>>> <!-- >>>> <Valve >>>> className="org.apache.catalina.valves.CometConnectionManagerValve" /> >>>> --> >>>> </Context> >>>> >>>> >>>>> what I find is. When I reach the limit, as expected the server will not >>>>> create a new session, however does return a http 200 status code. >>>>> >>>>> I am wondering would it be possible for me to change this behavior to >>>>> return say a 300 range code to redirect to (in a production >> environment) >>>>> load balancer. >>>>> >>>>> I can see some potential issues with this, like the possibility of an >>>>> infinite loop, but for now I am just exploring possible ways to prevent >>>> my >>>>> tomcat servers becoming overloaded. >>>> >>>> How do you have your load balancer setup now? What software / hardware >>>> are you using? What algorithm is it using to distribute the load? >>>> >>> Its an apache httpd server, distributing load using byRequest, with a >>> redundant fail-over node configured howevr this only works if the tomcat >>> server fails to accept the initial connection >>> >>>> >>>>> >>>>> Does anyone have any thoughts or ideas for this type of solution? >>>> >>>> Perhaps you need to adjust the load balancer so it's spreading out the >>>> connections more evenly? Perhaps you need to add another node to handle >>>> the load? >>>> >>>> Its a recent issue, typical user response to a slow application (for >>> whatever reason) is to open another session, however the jvmRoute is >> stored >>> in the browser which forces the 2nd,3rd,4th.... session to the same host. >>> >>> We are looking at a application solution to provide a new session without >>> the jvmRoute in separate tabs, but the ability to reject and redirect a >>> user (even to a error page) when the server limit we set is reached would >>> prevent a larger scale outage. >> >> You might try "maxConnections" on the HTTP connector. >> >> https://tomcat.apache.org/tomcat-7.0-doc/config/http.html >> >> or the AJP connector, depending on how your proxy is connecting to Tomcat. >> >> https://tomcat.apache.org/tomcat-7.0-doc/config/ajp.html >> >> "The maximum number of connections that the server will accept and process >> at any given time. When this number has been reached, the server will not >> accept any more connections until the number of connections falls below >> this value." >> >> Note this is different than the configuration you specified above, which >> appears like it's trying to restrict the number of sessions that the >> manager will create. >> >> Dan >> >> >> >> --------------------------------------------------------------------- >> To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org >> For additional commands, e-mail: users-h...@tomcat.apache.org >> >> > > > -- > *Mitchell Smith > * > Developer > *Cable & Wireless Communications* > Tel: +44 (0) 20 7315 4454 > Mobile: +44 (0) 7921619263 > www.cwc.com > > The information contained in this email (and any attachments) is confidential > and may be privileged. 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