Net::Server::PreForkSimple - Net::Server personality
use base qw(Net::Server::PreForkSimple);
sub process_request {
#...code...
}
__PACKAGE__->run();
Please read the pod on Net::Server first. This module is a personality, or
extension, or sub class, of the Net::Server module.
This personality binds to one or more ports and then forks
"max_servers" child processes. The server
will make sure that at any given time there are always
"max_servers" available to receive a
client request. Each of these children will process up to
"max_requests" client connections. This
type is good for a heavily hit site that can keep
"max_servers" processes dedicated to the
serving. (Multi port accept defaults to 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,
Net::Server::PreFork contains several other configurable parameters.
Key Value Default
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
max_dequeue \d+ undef
check_for_dequeue \d+ undef
- max_servers
- The maximum number of child servers to start and maintain. This does not
apply to dequeue processes.
- max_requests
- The number of client connections to receive before a child
terminates.
- serialize
- Determines whether the server serializes child connections. Options are
undef, flock, semaphore, pipe, or none. Default is undef. On multi_port
servers or on servers running on Solaris, the default is flock. The flock
option uses blocking exclusive flock on the file specified in
lock_file (see below). The semaphore option uses IPC::Semaphore
(thanks to Bennett Todd) for giving some sample code. The pipe option
reads on a pipe to choose the next. the flock option should be the most
bulletproof while the pipe option should be the most portable. (Flock is
able to reliquish the block if the process dies between accept on the
socket and reading of the client connection - semaphore and pipe do not).
An option of none will not perform any serialization. If "none"
is passed and there are multiple ports then a the default serialization
will be used insted of "none."
- lock_file
- Filename to use in flock serialized accept in order to serialize the
accept sequece between the children. This will default to a generated
temporary filename. If default value is used the lock_file will be removed
when the server closes.
- check_for_dead
- Seconds to wait before checking to see if a child died without letting the
parent know.
- max_dequeue
- The maximum number of dequeue processes to start. If a value of zero or
undef is given, no dequeue processes will be started. The number of
running dequeue processes will be checked by the check_for_dead
variable.
- check_for_dequeue
- Seconds to wait before forking off a dequeue process. The run_dequeue hook
must be defined when using this setting. It is intended to use the dequeue
process to take care of items such as mail queues. If a value of undef is
given, no dequeue processes will be started.
"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
max_servers 80
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
#-------------- file test.conf --------------
Process flow follows Net::Server until the loop phase. At this point
"max_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 always "max_servers"
running.
The PreForkSimple server has the following hooks in addition to the hooks
provided by the Net::Server base class. See Net::Server
- "$self->run_n_children_hook()"
- This hook occurs at the top of run_n_children which is called each time
the server goes to start more child processes. This gives the parent to do
a little of its own accountting (as desired). Idea for this hook came from
James FitzGibbon.
- "$self->child_init_hook()"
- This hook takes place immeditately after the child process forks from the
parent and before the child begins accepting connections. It is intended
for any addiotional chrooting or other security measures. It is suggested
that all perl modules be used by this point, so that the most shared
memory possible is used.
- "$self->child_finish_hook()"
- This hook takes place immediately before the child tells the parent that
it is exiting. It is intended for saving out logged information or other
general cleanup.
- "$self->run_dequeue()"
- This hook only gets called in conjunction with the check_for_dequeue
setting.
- "$self->idle_loop_hook()"
- This hook is called in every pass through the main process wait loop.
Since version 2.000, the PreForkSimple server has accepted the TTIN and TTOU
signals. When a TTIN is received, the max_servers is increased by 1. If a TTOU
signal is received the max_servers is 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.
Paul T. Seamons paul@seamons.com
Please see also Net::Server::Fork, Net::Server::INET, Net::Server::PreFork,
Net::Server::MultiType, Net::Server::Single Net::Server::SIG
Net::Server::Daemonize Net::Server::Proto