This series is about how connections are kept alive between different components along the route.
Browser - Load Balancer - Web Server - mod jk - Tomcat
Part 1 : Browser - Load Balancer.
Part 2 : Load Balancer - Apache HTTP Server
Part 3 : Apache HTTP Server - Mod jk
Load Balancer -> Apache Web Server
How is the connection between web server and load balancer maintained?
There is usually a seperate load balancer TCP profile for the connection between load balancer and the web servers. As described
here, the default "Idle Timeout" is 5 minutes and default "Keep Alive Interval" is 30 minutes.
When a request comes in for a page that takes a long time to render, a connection is established between the load balancer and the web server and can be observed by the netstat command.
> netstat -an | grep :81 |grep EST
tcp 0 0 ::ffff:111.111.111.11:81 ::ffff:111.111.111.12:55789 ESTABLISHED
After 5 minutes, netstat will show that the connection is gone, dropped by the load balancer even if the request is still being processed by downstream servers. So doesn't Apache web server send keep alive signals to the load balancer to maintain the connection, just as
Google Chrome does? The answer is no.