Server::Starter(3p)

NAME
Server::Starter - a superdaemon for hot-deploying server programs

SYNOPSIS
  # from command line
  % start_server --port=80 my_httpd

  # in my_httpd
  use Server::Starter qw(server_ports);

  my $listen_sock = IO::Socket::INET->new(
      Proto => 'tcp',
  );
  $listen_sock->fdopen((values %{server_ports()})[0], 'w')
      or die "failed to bind to listening socket:$!";

  while (1) {
      if (my $conn = $listen_sock->accept) {
          ....
      }
  }

DESCRIPTION
It is often a pain to write a server program that supports graceful restarts, with no resource leaks. Server::Starter, solves the problem by splitting the task into two. One is start_server, a script provided as a part of the module, which works as a superdaemon that binds to zero or more TCP ports, and repeatedly spawns the server program that actually handles the necessary tasks (for example, responding to incoming commenctions). The spawned server programs under Server::Starter call accept(2) and handle the requests.

The module can also be used to hot-deploy servers listening to unix domain sockets by omitting the --port option of start_server. In such case, the superdaemon will not bind to any TCP ports but instead concentrate on spawning the server program.

To gracefully restart the server program, send SIGHUP to the superdaemon. The superdaemon spawns a new server program, and if (and only if) it starts up successfully, sends SIGTERM to the old server program.

By using Server::Starter it is much easier to write a hot-deployable server. Following are the only requirements a server program to be run under Server::Starter should conform to:

- receive file descriptors to listen to through an environment variable - perform a graceful shutdown when receiving SIGTERM

A Net::Server personality that can be run under Server::Starter exists under the name Net::Server::SS::PreFork.

METHODS

server_ports
    Returns zero or more file descriptors on which the server program should call accept(2) in a hashref. Each element of the hashref is: (host:port|port)=file_descriptor.

start_server
    Starts the superdaemon. Used by the "start_server" scirpt.

AUTHOR
Kazuho Oku <kazuhooku@gmail.com> Copyright (C) 2009-2010 Cybozu Labs, Inc.

SEE ALSO
Net::Server::SS::PreFork

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