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| <modulesynopsis metafile="mod_lbmethod_bybusyness.xml.meta"> |
| |
| <name>mod_lbmethod_bybusyness</name> |
| <description>Pending Request Counting load balancer scheduler algorithm for <module |
| >mod_proxy_balancer</module></description> |
| <status>Extension</status> |
| <sourcefile>mod_lbmethod_bybusyness.c</sourcefile> |
| <identifier>lbmethod_bybusyness_module</identifier> |
| <compatibility>Split off from <module>mod_proxy_balancer</module> in 2.3</compatibility> |
| |
| <summary> |
| <p>This module does not provide any configuration directives of its own. |
| It requires the services of <module>mod_proxy_balancer</module>, and |
| provides the <code>bybusyness</code> load balancing method.</p> |
| </summary> |
| <seealso><module>mod_proxy</module></seealso> |
| <seealso><module>mod_proxy_balancer</module></seealso> |
| |
| <section id="busyness"> |
| |
| <title>Pending Request Counting Algorithm</title> |
| |
| <p>Enabled via <code>lbmethod=bybusyness</code>, this scheduler keeps |
| track of how many requests each worker is currently assigned at present. A new |
| request is automatically assigned to the worker with the lowest |
| number of active requests. This is useful in the case of workers |
| that queue incoming requests independently of Apache, to ensure that |
| queue length stays even and a request is always given to the worker |
| most likely to service it the fastest and reduce latency.</p> |
| |
| <p>In the case of multiple least-busy workers, the statistics (and |
| weightings) used by the Request Counting method are used to break the |
| tie. Over time, the distribution of work will come to resemble that |
| characteristic of <code>byrequests</code> (as implemented |
| by <module>mod_lbmethod_byrequests</module>).</p> |
| |
| </section> |
| |
| </modulesynopsis> |