Hi,
I am in the process of testing a move of our apache httpd & tomcat
application server from win2k3 to a solaris10 (5.10) environment.
Apache/2.2.8 (Unix) mod_ssl/2.2.8 OpenSSL/0.9.8h mod_jk/1.2.26
Apache Tomcat/6.0.16 running on java 1.6.0_07-b06
During testing I am seeing intermitent high load times for jsp pages. 20s+
when normally they are around 5s
To try and remove potential causes of the high load times I have been
removing layers of the application, ie oracle backend etc
Currently I am hitting a simple jsp directly on tomcat port 8080 this jsp
just has img tags to 10 jpg files 105756 bytes in size
<html>
<head></head>
<body>
<img src="images/100kb0.jpg">
<img src="images/100kb1.jpg">
<img src="images/100kb2.jpg">
<img src="images/100kb3.jpg">
<img src="images/100kb4.jpg">
<img src="images/100kb5.jpg">
<img src="images/100kb6.jpg">
<img src="images/100kb7.jpg">
<img src="images/100kb8.jpg">
<img src="images/100kb9.jpg">
</body>
</html>
Even this simple page is showing intermitent high load times 20s plus when
it is normally <5s
I have been using jmeter to run multiple tests of accessing this page and
this shows that the culprit for the long load time, however if I look in
the tomcat access log file it thinks it has served up the files as soon as
it has seen the request, it just gets the request 20 seconds later than the
previous, note that the second request below is recived 20s after the
first.
extract from tomcat access log
160.95.12.187 - - [09/Oct/2008:10:23:27 +0100] 0 0.000 GET
/dlTest/images/100kb1.jpg HTTP/1.1 200 -
160.95.12.187 - - [09/Oct/2008:10:23:48 +0100] 0 0.000 GET
/dlTest/images/100kb2.jpg HTTP/1.1 200 -
160.95.12.187 - - [09/Oct/2008:10:23:48 +0100] 0 0.000 GET
/dlTest/images/100kb3.jpg HTTP/1.1 200 -
looking at the snoop log of the network interface we see that a repeat
request has had to be made for this image, and is made 20s later
10:23:27.79488 l3bd5s3j.ced.corp.cummins.com -> redcstcttapdm01 HTTP GET
/dlTest/images/100kb1.jpg HTTP/1.1
10:23:27.80185 redcstcttapdm01 -> l3bd5s3j.ced.corp.cummins.com HTTP
HTTP/1.1 200 OK
10:23:28.31777 l3bd5s3j.ced.corp.cummins.com -> redcstcttapdm01 HTTP GET
/dlTest/images/100kb2.jpg HTTP/1.1
10:23:48.36992 l3bd5s3j.ced.corp.cummins.com -> redcstcttapdm01 HTTP GET
/dlTest/images/100kb2.jpg HTTP/1.1
10:23:48.37639 redcstcttapdm01 -> l3bd5s3j.ced.corp.cummins.com HTTP
HTTP/1.1 200 OK
10:23:48.90253 l3bd5s3j.ced.corp.cummins.com -> redcstcttapdm01 HTTP GET
/dlTest/images/100kb3.jpg HTTP/1.1
10:23:48.90934 redcstcttapdm01 -> l3bd5s3j.ced.corp.cummins.com HTTP
HTTP/1.1 200 OK
This 20s happens to coincide with the connectionTimeout in the server.xml
<Connector port="8080" protocol="HTTP/1.1"
connectionTimeout="20000"
maxThreads="150"
redirectPort="8443" />
Changing this to 2s i then see the delay in re-requests at 2s
9:00:29.00001 l3bd5s3j.ced.corp.cummins.com -> redcstcttapdm01 HTTP GET
/dlTest/images/100kb9.jpg HTTP/1.1
9:00:31.08255 l3bd5s3j.ced.corp.cummins.com -> redcstcttapdm01 HTTP GET
/dlTest/images/100kb9.jpg HTTP/1.1
I think I have eliminated the network and any possible client issues as
Apache will serve up this page over and over (basically the same page but
.html extension) with no slow loads, i have been using jmeter to make 100s
of requests for this page at different times of the day and not seen an
issue.
So I assume I am seeing some sort of connectionTimeout issue and the issue
is with tomcat.
I built tomcat from src using apache-ant-1.7.1 and java 1.5.0_06-b05 as I
was seeing issues when it was built under 1.6.0_07-b06, but running it
under the 1.6 version
My question is why am I seeing the request coming into the server on the
network card and it not being recieved by tomcat? Running top at the time
of these delays shows the server is idle, I am the only person testing on
this server.
Can any one shed any light on this?
Thanks
___________________________
Gary Johnstone
PLM System Administrator
Cummins Turbo Technologies Ltd
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