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.