Bug 37245 - Slow host in load balancer under heavy load issue
Summary: Slow host in load balancer under heavy load issue
Alias: None
Product: Tomcat Connectors
Classification: Unclassified
Component: Common (show other bugs)
Version: unspecified
Hardware: Other other
: P2 normal (vote)
Target Milestone: ---
Assignee: Tomcat Developers Mailing List
URL: http://algesten.blogspot.com/
Depends on: 36138
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Reported: 2005-10-26 08:09 UTC by Martin Algesten
Modified: 2008-10-05 03:09 UTC (History)
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Description Martin Algesten 2005-10-26 08:09:52 UTC
We have 1 web server dispatching requests to 4 application servers.

2 of these servers are older/slower/under more load from other sites being hosted.

When having a heavy load, we've observed that initially the busy queues of the workers are longer on 
the older hosts, which seems logical. However gradually increasing the load can reach a tipping point, 
where the older hosts can't get through the load quickly enough, making the queues grow and grow 
until tomcat stalls. This is happening at the same time as the two newer hosts are holding up fine and 
could take more load

An election algorithm that takes the busy queue into account would solve the problem. One such 
algorithm has been submitted in #36138.
Comment 1 Mladen Turk 2006-03-16 07:56:18 UTC
Commited #36138.
It will be part of the next 1.2.16