I am using Net::Server::Prefork to launch a TCP server. The startup routine looks like this:
use 5.10.1;
use strict;
use warnings;
use parent 'Net::Server::Fork';
Dispatcher->run(
'host' => $host || '*',
'port' => $port || 7000,
'ipv' => '*',
'log_level' => $main::config{'backend.loglevel'} || 0,
'log_file' => $main::config{'backend.logfile'} || undef,
'pid_file' => $main::config{'backend.pidfile'} || undef,
'user' => $main::config{'backend.user'} || 'nobody',
'group' => $main::config{'backend.group'} || 'nogroup',
'max_servers' => $main::config{'backend.maxconnections'} || 3,
'background' => !$main::config{'backend.foreground'} || undef,
'allow' => $main::config{'ip'} || '.*',
'reverse_lookups' => 1,
);
Dispatcher uses this function to process requests:
sub process_request {
eval {
local $SIG{'ALRM'} = sub { die "Timed Out!\n" };
my $previous_alarm = alarm($timeout);
my @args;
{
my $command = <STDIN>;
@args = split /\s+/, $command;
alarm($timeout);
}
alarm(($main::config{'timeout'} + 5) || 185);
{
Dispatcher::main(@args);
}
alarm($previous_alarm);
};
};
Now this is all good and well. However, when updating the server, I currently have the problem that in order not to kill requests that are in the midst of being processed, I have to check for active processes and wait until they are finished with the additional problem that while waiting new clients could connect. So - is there a chance to 'phase out' running child processes, i.e. terminate idle preforked processes, replace them with new version, and replace each running (old) process with a new version once the old process finishes?
Alternatively, can I block incoming connections until all old child processes are finished and then restart the server as a whole? I was thinking about doing this with temporary firewall rules, but would really prefer having perl handle this.
Any ideas are appreciated!
Have you tried to use leave_children_open_on_hup configuration option and restart server using HUP signal? [recipe for linux/unix]
It should work according to documentation.