Thanks for your Valuable Comments:
We are using Apache Tomcat/8.0.50 and Mod_JK mod_jk/1.2.28
The Above configuration made by some consultant. We are in the situation to
correct all the things to make it for high availability.
Also we are in the process of upgrading the apache to 2.4.25 with mod_jk/
1.2.42. And Event MPM instead of Prefork.
Please let us know do we need to use worker MPM also or EVENT MPM is fine?
If Event MPM with below Configuration then how many concurrent users can
access the site and what are the relevant changes needs to be done on
Tomcat Side?
On Tomcat Servers We have 16GB RAM with 8CPU [Two Nodes]
# event MPM
<IfModule event.c>
StartServers 1
ServerLimit 7
MinSpareThreads 250
MaxSpareThreads 2500
ThreadsPerChild 500
ThreadLimit 500
MaxRequestWorkers 3500
MaxConnectionsPerChild 0
</IfModule>
# Tomcat Configuration
<Connector port="9090" protocol="HTTP/1.1" redirectPort="8443"
URIEncoding="UTF-8" emptySessionPath="true" maxThreads="600"
minSpareThreads="10" connectionTimeout="-1" />
<Connector port="8009" protocol="AJP/1.3" redirectPort="8443"
URIEncoding="UTF-8" maxThreads="600" minSpareThreads="100"
connectionTimeout="20000" acceptCount="2000" />
# Tomcat Configuration
-Xms2048M -Xmx6144M -XX:PermSize=1024m -XX:MaxPermSize=2048m
On Thu, Dec 5, 2019 at 7:27 PM Christopher Schultz <
ch...@christopherschultz.net> wrote:
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> Jayaram,
>
> On 12/5/19 03:19, Jayaram Ponnusamy wrote:
> > We are using apache 2.2.21 on RHEL6.9 and in Backend we are using
> > Tomcat AppServer with JavaBased CMS. Our Server Architecture is
> > *(F5 [For Load Balance] -> Apache WebServer [For Redirection & URL
> > Mapping] -> Tomcat AppServer [Running a Java Based CMS]).*
>
> That version of Apache httpd is pretty old and unsupported. RHEL 6.9
> is also out of support (if I'm reading their Wikipedia page
> correctly). You may want to upgrade everything while you are looking
> at all this.
>
> > We are using Apache to connect Tomcat by MOD_JK and mapping the
> > URL (Attached VirtualHost.conf), and No applications/code are
> > running on WebServers.
> >
> > 1. Two TomcatServers (8 CPU & 16GB RAM on Each Servers) 2. Two
> > WebServers (4 CPU & 8GB RAM on Each Servers)
> >
> > *PROBLEM:* When the Child Process count is reached / crossed 200
> > like below then site is not accessible
>
> Do you mean that new connections from httpd -> Tomcat cannot be made?
>
> > when the child processes reached 300 or More than site crashed
>
> Please define "crashed". Got an exception? JVM crash (with hs_pid*
> file)? Kernel panic?
>
> > and then we bring the site back by restarting Tomcat & Apache
> > HTTP.
>
> Do you need to restart httpd? Or only Tomcat? Or will restarting httpd
> work?
>
> > Kindly please check my configuration and help to allow at-least
> > 500 concurrent users.
> >
> > *CONFIGURATION:* * httpd.conf* <IfModule prefork.c> StartServers
> > 80 ServerLimit 3500 MaxClients 3500 MaxRequestsPerChild 0
> > </IfModule> <IfModule worker.c> StartServers 6 MaxClients 230
> > MinSpareThreads 75 MaxSpareThreads 150 ThreadsPerChild 25
> > MaxRequestsPerChild 0 </IfModule>
>
> Which MPM are you actually using? You have listed both prefork and
> worker. AFAICT you have to pick one at runtime.
>
> For prefork, the maximum number of connections you should expect to be
> made to each Tomcat backend is 3500 (the value of MaxClients).
>
> For worker, the maximum number of connections you should expect to be
> made to each Tomcat backend is 230.
>
> > *Tomcat:* <Connector port="9090" protocol="HTTP/1.1"
> > redirectPort="8443" URIEncoding="UTF-8" emptySessionPath="true"
> > maxThreads="600" minSpareThreads="10" connectionTimeout="-1" />
> > <Connector port="8009" protocol="AJP/1.3" redirectPort="8443"
> > URIEncoding="UTF-8" maxThreads="600" minSpareThreads="100"
> > connectionTimeout="20000" acceptCount="2000" />
>
> Note that AJP connections are expected to be persistent; they don't
> close when the request has completed. They don't even really do "keep
> alive" in the same sense as HTTP keepalive. It's more like "always
> keepalive". Once an httpd process opens a connection to a Tomcat
> instance, that connection will remain open for quite a while as long
> as requests continue to be made.
>
> If you are using prefork MPM, the the version of Tomcat you are using
> is critical to understanding what is happening, here. If you are using
> a BIO-based connector, then you will need to increase the number of
> threads on each Tomcat server from 600 to 3500.
>
> If you are using the worker MPM, then your Tomcat should be able to
> handle the 230 maximum connections configured there.
>
> - -chris
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--
*Thanks & Regards,*
*Jayaram Ponnusamy*
Mobile: +974-5512-3315
