phpman > perldoc > Net::Server::PreFork(3pm)

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->new

        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.

    "$self->cleanup_dead_child_hook( $child )"
        This hook is called when a dead child is detected. A child is considered dead when the pid
        does no longer exist. This hook could be used to cleanup possible temporary files or locks
        left over by a dead child.

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 AT seamons.com

THANKS
    See Net::Server

SEE ALSO
    Please see also Net::Server::Fork, Net::Server::INET, Net::Server::PreForkSimple,
    Net::Server::MultiType, Net::Server::Single Net::Server::SIG Net::Server::Daemonize
    Net::Server::Proto