On 09/12/2019 06:41, Jayaram Ponnusamy wrote: > 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: > > 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.
TL;DR - Try switching to the NIO AJP connector on Tomcat. Take a look at this session I uploaded from TomcatCon London. You probably want to start around 35:00 and the topic of thread exhaustion. https://youtu.be/2QYWp1k5QQM Mark --------------------------------------------------------------------- To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org For additional commands, e-mail: users-h...@tomcat.apache.org
