Net::Server::PreFork - Net::Server personality
use base qw(Net::Server::PreFork);
sub process_request {
#...code...
}
__PACKAGE__->run();
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 the Net::Server::PreForkSimple manpage.
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.
Please see the sample listed in Net::Server.
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 the Net::Server::PreForkSimple manpage.
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 the Net::Server::PreForkSimple manpage.
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 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.
The PreFork server has the following hooks in addition to the hooks
provided by PreForkSimple. See the Net::Server::PreForkSimple manpage.
- $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.
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.
Tests don't seem to work on Win32. Any ideas or patches would be
welcome.
See the Net::Server manpage
Paul T. Seamons paul@seamons.com
See the Net::Server manpage
Please see also
the Net::Server::Fork manpage,
the Net::Server::INET manpage,
the Net::Server::PreForkSimple manpage,
the Net::Server::MultiType manpage,
the Net::Server::Single manpage
the Net::Server::SIG manpage
the Net::Server::Daemonize manpage
the Net::Server::Proto manpage
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