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From "Shapira, Yoav" <>
Subject RE: Problems with Tomcat in a high load environment
Date Fri, 01 Aug 2003 17:45:08 GMT

Even if your loathe to do it, a profiler is invaluable as long as the
profiled environment (your dev/test env) is close enough to production
to be meaningful.  You should profile, and run stress tests, on hardware
and software that's as similar as possible to production, before going

FWIW, 30 requests/sec is not an extremely high load: most of our apps
routinely handle several times that load on standalone tomcat 4.1.24
(and starting at 12:01 tonight, 4.1.27 ;))

Have you tried running without the IIS front-end?  It could be worth a
shot.  Tomcat can handle the static files as well.

Yoav Shapira
Millennium ChemInformatics

>-----Original Message-----
>Sent: Friday, August 01, 2003 1:29 PM
>Subject: Problems with Tomcat in a high load environment
>we are running Tomcat 4.1.18 on Windows 2000 under JDK1.4.1_01.  We are
>using IIS as a web server connecting using the ISAPI JK 2 connector.
>are currently experiencing 2 seperate problems when under high load (ie
>30 requests per second):
>1.  A huge number of log events (~30 sets per minute) are generated in
>NT event log which show problems with the ISAPI connector.  Each time
>there is a problem, 7 lines are created:
>Error: [jk_worker_ajp13.c (512)]: ajp13.service() Error  forwarding
>ajp13:localhost:8029 1 0
>Error: [jk_worker_ajp13.c (416)]: ajp13.service() ajpGetReply
>error 3
>Error: [jk_handler_response.c (178)]: handler.response() Error sending
>Error: [jk_service_iis.c (157)]: jk_ws_service_t::head,
>ServerSupportFunction failed
>Error: [jk_worker_ajp13.c (416)]: ajp13.service() ajpGetReply
>error 3
>Error: [jk_handler_response.c (200)]: Error ajp_process_callback -
>Error: [jk_service_iis.c (247)]: jk_ws_service_t::write, WriteClient
>These I think lead to the eventual crash of IIS however I also suspect
>that they may cause user errors though I havent actually seen any
>of this.  Does anyone know anything about these errors or what I can do
>reduce them?  Could it be a tuning of Tomcat issue?
>2. The server is set up currently with -Xms512m and the same for Xmx.
>This, I would have thought, was OK for this application, though of
>I could be wrong, but is in any case irrelevant to the problem as if I
>increase memory to 1Gb it makes no odds.
>The server will run fine for a few minutes at about 128m of memory
>At some (slightly random point with no obvious trigger), it will in a
>matter of seconds use up all available memory, thus triggering a huge
>in the processor usage which sits at roughly 50-60% (across 2
>constantly.  It is worth noting that 1 processor is not maxed out - the
>load is relatively evenly distributed.
>After a further while, the young generation space runs out of memory
and a
>process ensues of the processor load "bouncing" up to 100% and back to
>over and over again as it GCs, reduces the momery used to ~ 15m less
>it was, then it is used up again and so on.  This obviously seriously
>impacts the usage of the application.  I cant see why it is doing it;
>is an ecommerce application and the loads are not that high - clearly a
>leak of some description is occuring somewhere but the speed with which
>these changes happen baffle me, and I dont thik there is much setup
work I
>can do to change it.  I could install a profiler to find out whats
>on but it is a live system and I am loath to do so.
>Finally it is worth noting that I have only just made this system live
>a functionally identical although architecturally simpler version ran
>quite happily under the same loads using no more than 256m of ram under
>JRun 3.1.
>Any ideas?!
>Kiss Technologies
>4, Percy Street
>W1T 1DF
>Phone numbers:
>Phone 020 7692 9922
>Fax 020 7692 9923

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