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Net::Server::PreFork(3)              User Contributed Perl Documentation             Net::Server::PreFork(3)



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)  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'}.

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 -------------PROCESS

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, finishs 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 accountting (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

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



perl v5.16.2                                     2012-05-30                          Net::Server::PreFork(3)