Apache Load Balancing Algorithm Wrong Behaviour

Apache Load Balancing Algorithm Wrong Behaviour

Apache has 3 load balancing algorith: 1. Request Counting Algorithm 2.
Weighted Traffic Algorithm 3. Pending Request Counting Algorithm
Theoritically, pending request counting algorithm is better than the other
two because it will always try to choose web server with the least-active
connection.
I have 3 web servers and 1 load balancer. My question is, when I try
pending request counting algorithm, it didn't work as expected. It always
choose web server in round-robin basis (web server 1 -> web server 2 ->
web server 3 -> web server 1, and so on) Based on the theory, i expected
the result will be (web server 1 -> web server 1 -> web server 1, and so
on)
So, why is the pending request counting algorithm didn't work as expected?
NOTE: 1. No keep-alive connection. 2. To test the load balancer, i open a
simple page (less than 0,1s load time) and refresh it manually every 5 sec
to know which cluster it chose. 3. No changes made to configuration of
pending request counting algorithm.
Any help appreciated! Thanks before!