On 06.10.2017 11:57, Suvendu Sekhar Mondal wrote:
On Fri, Oct 6, 2017 at 2:06 AM, Jerry Malcolm <techst...@malcolms.com> wrote:
I am running TC 8.0 on WinServer8 on a commercially hosted platform with a
WAMP environment. I am running around 10 virtual hosts. 2 hosts are
dedicated to JSPWiki. The other 8 are running variations of the same custom
application with around 10-15 individual webapps each.
When I am running 7 of the 10 hosts, performance is great. I get JSP
response time under a second. But when I add just a couple of more of the
hosts, my page response time on all of the apps goes from an acceptable
under a second to horrible at around 15-20 seconds per page. It doesn't
seem to be a specific host causing the problem. Reducing overall hosts in
any order makes the problem go away.
I've looked at the the processor utilization during the good times and slow
times, and don't see a significant difference. I have 16GB of memory, and
it consistently shows about 35% utilization. I also checked mySQL response
time, and the per-query SQL response does not vary. So it doesn't appear to
be a db problem.
I suspect there is some TC configuration parameter such as heap, etc that I
need to tweak. (But I'm not getting OutOfMemory errors). But I don't know
which one, and I don't know a formula to use to figure out what to set it
to. So I just need a little education. What tools can I use to help me
figure out what is going south slowing everything to a crawl when the extra
hosts come online? And what parameters should I be looking at (and how
should I calculate the proper values based on number of hosts)?
Suggestions?
Interesting problem. Couple of questions:
Is the slowness sporadic or persistent? What happens when you again
shutdown some of the hosts? Does response time comes back to normal?
Is all transactions are slow or some of them which are routed to
specific host(s)?
Are you fronting Tomcat instances with Apache? If yes, then please
post BalancerMember configuration of the Tomcat cluster here.
Taking the OP's observations above at face value, I think that first thing that I would
do, is to configure the Java JVM that runs this tomcat, to do some logging of the Garbage
Collection events. And then I would look at that logfile, and find out if there is some
significant difference (in frequency of GC, or in the mounts of memory mentioned for each
event), depending on the number of Hosts enabled.
You would have to look at the appropriate command-line switches to use for the particular
JVM being used, for how to set this up.
And then (since this seems to be on a Windows platform, running tomcat as a service), you
should use the "tomcat(version)w.exe" program (a GUI), to set these parameters properly.
See e.g.
https://tomcat.apache.org/tomcat-8.5-doc/windows-service-howto.html#Tomcat_service_application
--> "Tomcat monitor application"
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