Load Balancing tomcat with Apache and mod jk

Tomcat works fairly under heavy loads. But many a times we would like to distribute the requests to more than one server to minimize response time and there by improving the user experience. This tutorial shows how to configure load balancing (distribute the load) between two tomcat instances in the same system (i have also shown how to do this for tomcat instances in two different servers). For this i am assuming you know how to install multiple tomcat instances in the same machine and also know how to connect apache with tomcat using mod_jk.

All we will do here is to add a new worker to the worker.properties file we already saw in the previous tutorials with Apache httpd 2.x, tomcat 6.x and tomcat-connector 1.2.27.

Below is the content of workers.properties file.

#
#workers.properties
#
# Below Entry Specifies the load balance factor when used with a load balancing worker.
# Note: ----> lbfactor must be > 0, Low lbfactor means less work done by the worker.
# worker.tomcat1.lbfactor=100 

# In Unix, we use forward slashes:
ps=/

# list the workers by name

# Workers that are member of lb should not be in the list.
worker.list = loadbalancer   

# ------------------------
# First worker
# ------------------------
worker.tomcat1.port=8009      # Give the ajp port of the first tomcat instance here
worker.tomcat1.host=localhost # You can mention any other hostname or IP here
worker.tomcat1.type=ajp13
worker.tomcat1.lbfactor=100    
worker.tomcat1.connection_pool_timeout=600
worker.tomcat1.socket_timeout=600
worker.tomcat1.recovery_options=16

# ------------------------
# Second worker
# ------------------------
worker.tomcat2.port=9009      # Give the ajp port of the first tomcat instance here
worker.tomcat2.host=localhost # You can mention any other hostname or IP here
worker.tomcat2.type=ajp13
worker.tomcat2.lbfactor=100
worker.tomcat2.connection_pool_timeout=600
worker.tomcat2.socket_timeout=600
worker.tomcat2.recovery_options=16

# ------------------------
# Load Balancer worker
# ------------------------
#
# The loadbalancer (type lb) worker performs weighted round-robin
# load balancing with sticky sessions.
# Note:
# ----> If a worker dies, the load balancer will check its state
#once in a while. Until then all work is redirected to peer
# worker.
worker.loadbalancer.type=lb
worker.loadbalancer.balance_workers=tomcat1, tomcat2
worker.loadbalancer.sticky_session=False
worker.loadbalancer.sticky_session_force=False

# END workers.properties
 

Note: You can have as many tomcat instances(workers) as you want in the same box as long as your box can withstand the load.