Ubuntu Manpage: Net::Server::PreFork - Net::Server personality

Provided by: libnet-server-perl_2.007-3_all

NAME

       Net::Server::PreFork - Net::Server personality

SYNOPSIS

           use base qw(Net::Server::PreFork);

           sub process_request {
               #...code...
           }

           __PACKAGE__->run();

DESCRIPTION

       Please read the pod on Net::Server and Net::Server::PreForkSimple first.  This module is a
       personality, or extension, or sub class, of the Net::Server::PreForkSimple class which is
       a sub class of Net::Server.  See Net::Server::PreForkSimple.

       This personality binds to one or more ports and then forks "min_servers" child process.
       The server will make sure that at any given time there are "min_spare_servers" available
       to receive a client request, up to "max_servers".  Each of these children will process up
       to "max_requests" client connections.  This type is good for a heavily hit site, and
       should scale well for most applications.  (Multi port accept is accomplished using flock
       to serialize the children).

       At this time, it does not appear that this module will pass tests on Win32 systems.  Any
       ideas or patches for making the tests pass would be welcome.

SAMPLE CODE

       Please see the sample listed in Net::Server.

COMMAND LINE ARGUMENTS

In addition to the command line arguments of the Net::Server base class and the
Net::Server::PreForkSimple parent class, Net::Server::PreFork contains several other
configurable parameters. You really should also see Net::Server::PreForkSimple.

Key Value Default
min_servers \d+ 5
min_spare_servers \d+ 2
max_spare_servers \d+ 10
max_servers \d+ 50
max_requests \d+ 1000

serialize (flock|semaphore
|pipe|none) undef
# serialize defaults to flock on multi_port or on Solaris
lock_file "filename" File::Temp::tempfile or POSIX::tmpnam

check_for_dead \d+ 30
check_for_waiting \d+ 10

max_dequeue \d+ undef
check_for_dequeue \d+ undef

child_communication 1 undef

min_servers
The minimum number of servers to keep running.

min_spare_servers
The minimum number of servers to have waiting for requests. Minimum and maximum
numbers should not be set to close to each other or the server will fork and kill
children too often.

max_spare_servers
The maximum number of servers to have waiting for requests. See min_spare_servers.

max_servers
The maximum number of child servers to start. This does not apply to dequeue
processes.

check_for_waiting
Seconds to wait before checking to see if we can kill off some waiting servers.

check_for_spawn
Seconds between checking to see if we need to spawn more children

min_child_ttl
Minimum number of seconds between starting children and killing a child process

child_communication
Enable child communication to parent via unix sockets. If set to true, will let
children write to the socket contained in $self->{'server'}->{'parent_sock'}. The
parent will be notified through child_is_talking_hook where the first argument is the
socket to the child. The child's socket is stored in
$self->{'server'}->{'children'}->{$child_pid}->{'sock'}.

serialize
See the documentation under Net::Server::PreForkSimple.

CONFIGURATION FILE

       "Net::Server::PreFork" allows for the use of a configuration file to read in server
       parameters.  The format of this conf file is simple key value pairs.  Comments and white
       space are ignored.

           #-------------- file test.conf --------------

           ### server information
           min_servers   20
           max_servers   80
           min_spare_servers 10
           min_spare_servers 15

           max_requests  1000

           ### user and group to become
           user        somebody
           group       everybody

           ### logging ?
           log_file    /var/log/server.log
           log_level   3
           pid_file    /tmp/server.pid

           ### access control
           allow       .+\.(net|com)
           allow       domain\.com
           deny        a.+

           ### background the process?
           background  1

           ### ports to bind
           host        127.0.0.1
           port        localhost:20204
           port        20205

           ### reverse lookups ?
           # reverse_lookups on

           ### enable child communication ?
           # child_communication

           #-------------- file test.conf --------------

PROCESS FLOW

       Process flow follows Net::Server until the loop phase.  At this point "min_servers" are
       forked and wait for connections.  When a child accepts a connection, finishes processing a
       client, or exits, it relays that information to the parent, which keeps track and makes
       sure there are enough children to fulfill "min_servers", "min_spare_servers",
       "max_spare_servers", and "max_servers".

HOOKS

       The PreFork server has the following hooks in addition to the hooks provided by
       PreForkSimple.  See Net::Server::PreForkSimple.

       "$self->run_n_children_hook()"
           This hook occurs at the top of run_n_children which is called each time the server
           goes to start more child processes.  This gives the parent to do a little of its own
           accounting (as desired).  Idea for this hook came from James FitzGibbon.

       "$self->parent_read_hook()"
           This hook occurs any time that the parent reads information from the child.  The line
           from the child is sent as an argument.

       "$self->child_is_talking_hook()"
           This hook occurs if child_communication is true and the child has written to
           $self->{'server'}->{'parent_sock'}.  The first argument will be the open socket to the
           child.

       "$self->idle_loop_hook()"
           This hook is called in every pass through the main process wait loop, every
           "check_for_waiting" seconds.  The first argument is a reference to an array of file
           descriptors that can be read at the moment.

HOT DEPLOY

       Since version 2.000, the PreFork server has accepted the TTIN and TTOU signals.  When a
       TTIN is received, the min and max_servers are increased by 1.  If a TTOU signal is
       received the min max_servers are decreased by 1.  This allows for adjusting the number of
       handling processes without having to restart the server.

BUGS

       Tests don't seem to work on Win32.  Any ideas or patches would be welcome.

TO DO

       See Net::Server

AUTHOR

       Paul T. Seamons paul@seamons.com

THANKS

       See Net::Server