Net::Server::PreForkSimple(3pm)

1Net::Server::PreForkSimUpsleer(3C)ontributed Perl DocumeNnetta:t:iSoenrver::PreForkSimple(3)
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NAME

6       Net::Server::PreForkSimple - Net::Server personality
7

SYNOPSIS

9           use base qw(Net::Server::PreForkSimple);
10
11           sub process_request {
12               #...code...
13           }
14
15           __PACKAGE__->run();
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DESCRIPTION

18       Please read the pod on Net::Server first.  This module is a
19       personality, or extension, or sub class, of the Net::Server module.
20
21       This personality binds to one or more ports and then forks
22       "max_servers" child processes.  The server will make sure that at any
23       given time there are always "max_servers" available to receive a client
24       request.  Each of these children will process up to "max_requests"
25       client connections.  This type is good for a heavily hit site that can
26       keep "max_servers" processes dedicated to the serving.  (Multi port
27       accept defaults to using flock to serialize the children).
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29       At this time, it does not appear that this module will pass tests on
30       Win32 systems.  Any ideas or patches for making the tests pass would be
31       welcome.
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SAMPLE CODE

34       Please see the sample listed in Net::Server.
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COMMAND LINE ARGUMENTS

37       In addition to the command line arguments of the Net::Server base
38       class, Net::Server::PreFork contains several other configurable
39       parameters.
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41           Key               Value                   Default
42           max_servers       \d+                     50
43           max_requests      \d+                     1000
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45           serialize         (flock|semaphore
46                              |pipe|none)  undef
47           # serialize defaults to flock on multi_port or on Solaris
48           lock_file         "filename"              File::Temp->new
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50           check_for_dead    \d+                     30
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52           max_dequeue       \d+                     undef
53           check_for_dequeue \d+                     undef
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55       max_servers
56           The maximum number of child servers to start and maintain.  This
57           does not apply to dequeue processes.
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59       max_requests
60           The number of client connections to receive before a child
61           terminates.
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63       serialize
64           Determines whether the server serializes child connections.
65           Options are undef, flock, semaphore, pipe, or none.  Default is
66           undef.  On multi_port servers or on servers running on Solaris, the
67           default is flock.  The flock option uses blocking exclusive flock
68           on the file specified in lock_file (see below).  The semaphore
69           option uses IPC::Semaphore (thanks to Bennett Todd) for giving some
70           sample code.  The pipe option reads on a pipe to choose the next.
71           the flock option should be the most bulletproof while the pipe
72           option should be the most portable.  (Flock is able to reliquish
73           the block if the process dies between accept on the socket and
74           reading of the client connection - semaphore and pipe do not).  An
75           option of none will not perform any serialization.  If "none" is
76           passed and there are multiple ports then a the default
77           serialization will be used insted of "none."
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79       lock_file
80           Filename to use in flock serialized accept in order to serialize
81           the accept sequece between the children.  This will default to a
82           generated temporary filename.  If default value is used the
83           lock_file will be removed when the server closes.
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85       check_for_dead
86           Seconds to wait before checking to see if a child died without
87           letting the parent know.
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89       max_dequeue
90           The maximum number of dequeue processes to start.  If a value of
91           zero or undef is given, no dequeue processes will be started.  The
92           number of running dequeue processes will be checked by the
93           check_for_dead variable.
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95       check_for_dequeue
96           Seconds to wait before forking off a dequeue process.  The
97           run_dequeue hook must be defined when using this setting.  It is
98           intended to use the dequeue process to take care of items such as
99           mail queues.  If a value of undef is given, no dequeue processes
100           will be started.
101

CONFIGURATION FILE

103       "Net::Server::PreFork" allows for the use of a configuration file to
104       read in server parameters.  The format of this conf file is simple key
105       value pairs.  Comments and white space are ignored.
106
107           #-------------- file test.conf --------------
108
109           ### server information
110           max_servers   80
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112           max_requests  1000
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114           ### user and group to become
115           user        somebody
116           group       everybody
117
118           ### logging ?
119           log_file    /var/log/server.log
120           log_level   3
121           pid_file    /tmp/server.pid
122
123           ### access control
124           allow       .+\.(net|com)
125           allow       domain\.com
126           deny        a.+
127
128           ### background the process?
129           background  1
130
131           ### ports to bind
132           host        127.0.0.1
133           port        localhost:20204
134           port        20205
135
136           ### reverse lookups ?
137           # reverse_lookups on
138
139           #-------------- file test.conf --------------
140

PROCESS FLOW

142       Process flow follows Net::Server until the loop phase.  At this point
143       "max_servers" are forked and wait for connections.  When a child
144       accepts a connection, finishs processing a client, or exits, it relays
145       that information to the parent, which keeps track and makes sure there
146       are always "max_servers" running.
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HOOKS

149       The PreForkSimple server has the following hooks in addition to the
150       hooks provided by the Net::Server base class.  See Net::Server
151
152       "$self->run_n_children_hook()"
153           This hook occurs at the top of run_n_children which is called each
154           time the server goes to start more child processes.  This gives the
155           parent to do a little of its own accountting (as desired).  Idea
156           for this hook came from James FitzGibbon.
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158       "$self->child_init_hook()"
159           This hook takes place immeditately after the child process forks
160           from the parent and before the child begins accepting connections.
161           It is intended for any addiotional chrooting or other security
162           measures.  It is suggested that all perl modules be used by this
163           point, so that the most shared memory possible is used.
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165       "$self->child_finish_hook()"
166           This hook takes place immediately before the child tells the parent
167           that it is exiting.  It is intended for saving out logged
168           information or other general cleanup.
169
170       "$self->run_dequeue()"
171           This hook only gets called in conjunction with the
172           check_for_dequeue setting.
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174       "$self->idle_loop_hook()"
175           This hook is called in every pass through the main process wait
176           loop.
177

HOT DEPLOY

179       Since version 2.000, the PreForkSimple server has accepted the TTIN and
180       TTOU signals.  When a TTIN is received, the max_servers is increased by
181       1.  If a TTOU signal is received the max_servers is decreased by 1.
182       This allows for adjusting the number of handling processes without
183       having to restart the server.
184

BUGS

186       Tests don't seem to work on Win32.  Any ideas or patches would be
187       welcome.
188

TO DO

190       See Net::Server
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AUTHOR

193       Paul T. Seamons paul@seamons.com
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THANKS

196       See Net::Server
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