Starlet - a simple, high-performance PSGI/Plack HTTP server


  % start_server --port=80 -- plackup -s Starlet [options] your-app.psgi

  or if you do not need hot deploy,

  % plackup -s Starlet --port=80 [options] your-app.psgi


Starlet is a standalone HTTP/1.1 web server, formerly known as Plack::Server::Standalone::Prefork and Plack::Server::Standalone::Prefork::Server::Starter.

The server supports following features, and is suitable for running HTTP application servers behind a reverse proxy.

- prefork and graceful shutdown using Parallel::Prefork

- hot deploy using Server::Starter

- fast HTTP processing using HTTP::Parser::XS (optional)


In addition to the options supported by plackup, Starlet accepts following options(s).


number of worker processes (default: 10)


seconds until timeout (default: 300)


timeout for persistent connections (default: 2)


max. number of requests allowed per single persistent connection. If set to one, persistent connections are disabled (default: 1)


max. number of requests to be handled before a worker process exits (default: 100)


if set, randomizes the number of requests handled by a single worker process between the value and that supplied by --max-reqs-per-chlid (default: none)


if set, worker processes will not be spawned more than once than every given seconds. Also, when SIGHUP is being received, no more than one worker processes will be collected every given seconds. This feature is useful for doing a "slow-restart". See for more information. (default: none)


the subroutine code to be executed right before a child process exits. e.g. --child-exit='sub { POSIX::_exit(0) }'. (default: none)

Extensions to PSGI


Starlets exposes a callback named psgix.informational that can be used for sending an informational response. The callback accepts two arguments, the first argument being the status code and the second being an arrayref of the headers to be sent. Example below sends an 103 response before processing the request to build a final response.

  sub {
      my $env = shift;
      $env["psgix.informational"}->(103, [
        'link' => '</style.css>; rel=preload'
      my $resp = ... application logic ...


Starlet is designed and implemented to be simple, secure and fast, especially for running as an HTTP application server running behind a reverse proxy. It only depends on a minimal number of well-designed (and well-focused) modules.


Parallel::Prefork Starman Server::Starter


Kazuho Oku



Tomohiro Takezawa


This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.