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.\"
.IX Title "Server::Starter 3pm"
.TH Server::Starter 3pm "2018-03-11" "perl v5.26.1" "User Contributed Perl Documentation"
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
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.SH "NAME"
Server::Starter \- a superdaemon for hot\-deploying server programs
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 2
\&  # 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 => \*(Aqtcp\*(Aq,
\&  );
\&  $listen_sock\->fdopen((values %{server_ports()})[0], \*(Aqw\*(Aq)
\&      or die "failed to bind to listening socket:$!";
\&
\&  while (1) {
\&      if (my $conn = $listen_sock\->accept) {
\&          ....
\&      }
\&  }
.Ve
.SH "DESCRIPTION"
.IX Header "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 \s-1TCP\s0 ports or unix sockets, and repeatedly spawns the server program that actually handles the necessary tasks (for example, responding to incoming connections).  The spawned server programs under Server::Starter call \fIaccept\fR\|(2) and handle the requests.
.PP
To gracefully restart the server program, send \s-1SIGHUP\s0 to the superdaemon.  The superdaemon spawns a new server program, and if (and only if) it starts up successfully, sends \s-1SIGTERM\s0 to the old server program.
.PP
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:
.IP "\(bu" 4
receive file descriptors to listen to through an environment variable
.IP "\(bu" 4
perform a graceful shutdown when receiving \s-1SIGTERM\s0
.PP
A Net::Server personality that can be run under Server::Starter exists under the name Net::Server::SS::PreFork.
.SH "METHODS"
.IX Header "METHODS"
.IP "server_ports" 4
.IX Item "server_ports"
Returns zero or more file descriptors on which the server program should call \fIaccept\fR\|(2) in a hashref.  Each element of the hashref is: (host:port|port|path_of_unix_socket) => file_descriptor.
.IP "start_server" 4
.IX Item "start_server"
Starts the superdaemon.  Used by the \f(CW\*(C`start_server\*(C'\fR script.
.SH "AUTHOR"
.IX Header "AUTHOR"
Kazuho Oku
.SH "SEE ALSO"
.IX Header "SEE ALSO"
Net::Server::SS::PreFork
.SH "LICENSE"
.IX Header "LICENSE"
This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.