Perl-based reverse proxy load balancer and web server

 Perlbal is a single-threaded event-based server supporting HTTP load
 balancing, web serving, and a mix of the two. Perlbal can act as either a web
 server or a reverse proxy.
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 One of the defining things about Perlbal is that almost everything can be
 configured or reconfigured on the fly without needing to restart the software.
 A basic configuration file containing a management port enables you to easily
 perform operations on a running instance of Perlbal.
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 Perlbal can also be extended by means of per-service (and global) plugins that
 can override many parts of request handling and behavior.