Howdy, Going back to your original message, it seems that things get out of hand when a server retrieves a large result set. Can you test the case when you have only a few users, but they ask for large amounts of information? Maybe something in the result set processing code is a hog..
Yoav Shapira Millennium ChemInformatics >-----Original Message----- >From: Dov Rosenberg [mailto:[EMAIL PROTECTED] >Sent: Wednesday, March 05, 2003 4:40 PM >To: Tomcat Users List >Subject: Re: Tomcat 4.1.18: 500+ Servlets locks up on Solaris under load > >We have profiled the app using JProbe and a couple of other tools. >Nearly all of the servlets are very simple. They open a connection >(from a pool), execute a query, cycle thru the result set, and then >close everything (result sets, statements, connection, etc). > >The profiler does not show any hotspots in the code to speak of. Most >of the servlets simply have a bunch of > out.println(.....); >statements in them. > >We are moving to JDK 1.3.x because we have another app that can't run >under 1.4.x yet. I'm not sure if there is much benefit going from 1.3.0 >to 1.3.1x, but I am willing to try if that will help. > >Dov Rosenberg > >On Wednesday, March 5, 2003, at 04:28 PM, Shapira, Yoav wrote: > >> >> Howdy, >> I would suggest profiling just your application, if possible, without a >> web server at all. Alternatively, run the web server with a profiler >> (OptimizeIt, JProbe, etc.) and try to allocate memory leaks. The >> profiler will show tomcat classes as well, so you can try to look for >> memory leaks there, but I doubt you'd find any. >> >> When profiling, be careful not to do it on your production server, as >> running with a profiler will slow things down a whole lot. >> >> As a side note: JDK 1.1.7 is really old. You app may greatly benefit >> from taking advantage of some of the newer features available in JDK >> 1.4. >> >> Yoav Shapira >> Millennium ChemInformatics >> >> >>> -----Original Message----- >>> From: Dov Rosenberg [mailto:[EMAIL PROTECTED] >>> Sent: Wednesday, March 05, 2003 4:24 PM >>> To: Tomcat Users List >>> Subject: Re: Tomcat 4.1.18: 500+ Servlets locks up on Solaris under >> load >>> >>> I'm not sure if Tomcat is totally to blame, I'm sure when I figure out >>> the problem it will point to our code. >>> >>> The reason I suspect Tomcat at this point is when the app is not under >>> load (i.e. using Jmeter to simulate 10-20 user concurrent load) the >>> app >>> seems OK. the response times are acceptable even under as long as a >>> servlet doesn't retrieve a lot of data. (I didn't write the app, just >>> trying to fix it). The app is running fairly well under JDK 1.17 on >>> Java WebServer on NT but falls on its knees under JDK 1.3.0 and Tomcat >>> 4.1.18. >>> >>> We have done a bunch of other things on Tomcat (not 4.1.18) without >>> having this kind of behavior. >>> >>> Dov Rosenberg >>> >>> On Wednesday, March 5, 2003, at 04:10 PM, Shapira, Yoav wrote: >>> >>>> >>>> Howdy, >>>> Given >>>> "once a servlet >>>> loads that retrieves a bunch of data, the CPU processing starts to >>>> increase until it pegs at 99% (according to TOP). All users then stop >>>> responding. The only way to recover is to terminate the process and >>>> restart Tomcat. The garbage collection indicates when the app becomes >>>> unresponsive the garbage collection shows a lot of full garbage >>>> collection cycles but the app never recovers - it essentially goes >> into >>>> an endless loop." >>>> what makes you think this is a tomcat problem, as opposed to for >>>> example >>>> a loop in your app or a memory leak in your app? >>>> >>>> Yoav Shapira >>>> Millennium ChemInformatics >>>> >>>> >>>>> -----Original Message----- >>>>> From: Dov Rosenberg [mailto:[EMAIL PROTECTED] >>>>> Sent: Wednesday, March 05, 2003 3:57 PM >>>>> To: [EMAIL PROTECTED] >>>>> Subject: Tomcat 4.1.18: 500+ Servlets locks up on Solaris under load >>>>> >>>>> I have a Solaris server running Tomcat 4.1.18 and Java 1.3.0 with a >>>>> single CPU and 2GIG RAM. The application has 500+ servlets that were >>>>> originally developed under JDK 1.17b to run under the old Java Web >>>>> Server on Windows NT4. The old system seems to handle the load much >>>>> better than the new version. We have configured the Invoker to load >>>>> the >>>>> servlets automatically instead of explicitly naming them in the >>>> web.xml. >>>>> >>>>> I am launching the Tomcat server with the following parameters: >>>>> >>>>> -server -Xms384m -Xmx384m -XX:NewSize=128m -XX:MaxNewSize=128m >>>>> -Xconcurrentio -Xincgc -verbose:gc >>>>> >>>>> under load the Tomcat server runs fine for a bit but once a servlet >>>>> loads that retrieves a bunch of data, the CPU processing starts to >>>>> increase until it pegs at 99% (according to TOP). All users then >> stop >>>>> responding. The only way to recover is to terminate the process and >>>>> restart Tomcat. The garbage collection indicates when the app >> becomes >>>>> unresponsive the garbage collection shows a lot of full garbage >>>>> collection cycles but the app never recovers - it essentially goes >>>>> into >>>>> an endless loop. >>>>> >>>>> Some of the parameters in our server.xml are: >>>>> >>>>> <Connector className="org.apache.coyote.tomcat4.CoyoteConnector" >>>>> redirectPort="443" bufferSize="2048" port="8009" >> connectionTimeout="0" >>>>> scheme="http" enableLookups="true" secure="false" >>>>> protocolHandlerClassName="org.apache.jk.server.JkCoyoteHandler" >>>>> debug="9" disableUploadTimeout="false" ProxyPort="0" >>>>> maxProcessors="75" >>>>> minProcessors="5" tcpNoDelay="true" acceptCount="10" >>>>> useURIValidationHack="false"> >>>>> <Factory >>>>> className="org.apache.catalina.net.DefaultServerSocketFactory"/> >>>>> </Connector> >>>>> >>>>> <Connector className="org.apache.coyote.tomcat4.CoyoteConnector" >>>>> redirectPort="-1" bufferSize="2048" port="80" connectionTimeout="0" >>>>> scheme="http" enableLookups="true" secure="false" >>>>> protocolHandlerClassName="org.apache.coyote.http11.Http11Protocol" >>>>> debug="9" disable UploadTimeout="false" proxyPort="0" >>>>> maxProcessors="-1" minProcessors="5" tcpNoDelay="true" >>>>> acceptCount="10" >>>>> useURIValidationHack="true"> >>>>> <Factory >>>>> className="org.apache.catalina.net.DefaultServerSocketFactory"/> >>>>> </Connector> >>>>> >>>>> >>>>> I am running Tomcat on port 80 as the root user if that has any >>>>> bearing >>>>> on things. Originally we had Apache in the mix, but to simplify >>>>> figuring out the problems we have configured Tomcat to act as the >> web >>>>> server for the time being. Some of the static resource directories >> are >>>>> symbolic links. >>>>> >>>>> Dov Rosenberg >>>>> Conviveon Corporation >>>>> 407-339-1177 ext 102 >>>>> >>>>> >>>>> >> --------------------------------------------------------------------- >>>>> To unsubscribe, e-mail: [EMAIL PROTECTED] >>>>> For additional commands, e-mail: [EMAIL PROTECTED] >>>> >>>> >>>> >>>> >>>> This e-mail, including any attachments, is a confidential business >>>> communication, and may contain information that is confidential, >>>> proprietary and/or privileged. This e-mail is intended only for the >>>> individual(s) to whom it is addressed, and may not be saved, copied, >>>> printed, disclosed or used by anyone else. 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