NAME¶
FCGI::ProcManager - functions for managing FastCGI applications.
SYNOPSIS¶
# In Object-oriented style.
use CGI::Fast;
use FCGI::ProcManager;
my $proc_manager = FCGI::ProcManager->new({
n_processes => 10
});
$proc_manager->pm_manage();
while (my $cgi = CGI::Fast->new()) {
$proc_manager->pm_pre_dispatch();
# ... handle the request here ...
$proc_manager->pm_post_dispatch();
}
# This style is also supported:
use CGI::Fast;
use FCGI::ProcManager qw(pm_manage pm_pre_dispatch
pm_post_dispatch);
pm_manage( n_processes => 10 );
while (my $cgi = CGI::Fast->new()) {
pm_pre_dispatch();
#...
pm_post_dispatch();
}
DESCRIPTION¶
FCGI::ProcManager is used to serve as a FastCGI process manager. By
re-implementing it in perl, developers can more finely tune performance in
their web applications, and can take advantage of copy-on-write semantics
prevalent in UNIX kernel process management. The process manager should be
invoked before the caller''s request loop
The primary routine, "pm_manage", enters a loop in which it maintains
a number of FastCGI servers (via
fork(2)), and which reaps those
servers when they die (via
wait(2)).
"pm_manage" provides too hooks:
C<managing_init> - called just before the manager enters the manager loop.
C<handling_init> - called just before a server is returns from C<pm_manage>
It is necessary for the caller, when implementing its request loop, to insert a
call to "pm_pre_dispatch" at the top of the loop, and then
7"pm_post_dispatch" at the end of the loop.
Signal Handling¶
FCGI::ProcManager attempts to do the right thing for proper shutdowns now.
When it receives a SIGHUP, it sends a SIGTERM to each of its children, and then
resumes its normal operations.
When it receives a SIGTERM, it sends a SIGTERM to each of its children, sets an
alarm(3) "die timeout" handler, and waits for each of its
children to die. If all children die before this timeout, process manager
exits with return status 0. If all children do not die by the time the
"die timeout" occurs, the process manager sends a SIGKILL to each of
the remaining children, and exists with return status 1.
In order to get FastCGI servers to exit upon receiving a signal, it is necessary
to use its FAIL_ACCEPT_ON_INTR. See FCGI's description of FAIL_ACCEPT_ON_INTR.
Unfortunately, if you want/need to use CGI::Fast, it is currently necessary to
run the latest (at the time of writing) development version of FCGI.pm. (>=
0.71_02)
Otherwise, if you don't, there is a loop around
accept(2) which prevents
os_unix.c
OS_Accept() from returning the necessary error when FastCGI
servers blocking on
accept(2) receive the SIGTERM or SIGHUP.
FCGI::ProcManager uses
POSIX::sigaction() to override the default
SA_RESTART policy used for perl's %SIG behavior. Specifically, the process
manager never uses SA_RESTART, while the child FastCGI servers turn off
SA_RESTART around the
accept(2) loop, but re-enstate it otherwise.
The desired (and implemented) effect is to give a request as big a chance as
possible to succeed and to delay their exits until after their request, while
allowing the FastCGI servers waiting for new requests to die right away.
METHODS¶
new¶
class or instance
(ProcManager) new([hash parameters])
Constructs a new process manager. Takes an option has of initial parameter
values, and assigns these to the constructed object HASH, overriding any
default values. The default parameter values currently are:
role => manager
start_delay => 0
die_timeout => 60
pm_title => 'perl-fcgi-pm'
Manager methods¶
pm_manage¶
instance or export
(int) pm_manage([hash parameters])
DESCRIPTION:
When this is called by a FastCGI script to manage application servers. It
defines a sequence of instructions for a process to enter this method and
begin forking off and managing those handlers, and it defines a sequence of
instructions to intialize those handlers.
If n_processes < 1, the managing section is subverted, and only the handling
sequence is executed.
Either returns the return value of
pm_die() and/or
pm_abort()
(which will not ever return in general), or returns 1 to the calling script to
begin handling requests.
managing_init¶
instance
() managing_init()
DESCRIPTION:
Overrideable method which initializes a process manager. In order to handle
signals, manage the PID file, and change the process name properly, any method
which overrides this should call
SUPER::managing_init().
pm_die¶
instance or export
() pm_die(string msg[, int exit_status])
DESCRIPTION:
This method is called when a process manager receives a notification to shut
itself down.
pm_die() attempts to shutdown the process manager gently,
sending a SIGTERM to each managed process, waiting
die_timeout()
seconds to reap each process, and then exit gracefully once all children are
reaped, or to abort if all children are not reaped.
pm_wait¶
instance or export
(int pid) pm_wait()
DESCRIPTION:
This calls
wait() which suspends execution until a child has exited. If
the process ID returned by wait corresponds to a managed process,
pm_notify() is called with the exit status of that process.
pm_wait() returns with the return value of
wait().
pm_write_pid_file¶
instance or export
() pm_write_pid_file([string filename])
DESCRIPTION:
Writes current process ID to optionally specified file. If no filename is
specified, it uses the value of the "pid_fname" parameter.
pm_remove_pid_file¶
instance or export
() pm_remove_pid_file()
DESCRIPTION:
Removes optionally specified file. If no filename is specified, it uses the
value of the "pid_fname" parameter.
sig_sub¶
instance
() sig_sub(string name)
DESCRIPTION:
The name of this method is passed to
POSIX::sigaction(), and handles
signals for the process manager. If $SIG_CODEREF is set, then the input
arguments to this are passed to a call to that.
sig_manager¶
instance
() sig_manager(string name)
DESCRIPTION:
Handles signals of the process manager. Takes as input the name of signal being
handled.
Handler methods¶
handling_init¶
instance or export
() handling_init()
DESCRIPTION:
pm_pre_dispatch¶
instance or export
() pm_pre_dispatch()
DESCRIPTION:
pm_post_dispatch¶
instance or export
() pm_post_dispatch()
DESCRIPTION:
sig_handler¶
instance or export
() sig_handler()
DESCRIPTION:
Common methods and routines¶
self_or_default¶
private global
(ProcManager, @args) self_or_default([ ProcManager, ] @args);
DESCRIPTION:
This is a helper subroutine to acquire or otherwise create a singleton default
object if one is not passed in, e.g., a method call.
pm_change_process_name¶
instance or export
() pm_change_process_name()
DESCRIPTION:
pm_received_signal¶
instance or export
() pm_received signal()
DESCRIPTION:
parameters¶
pm_parameter¶
instance or export
() pm_parameter()
DESCRIPTION:
n_processes¶
no_signals¶
pid_fname¶
die_timeout¶
role¶
start_delay¶
DESCRIPTION:
notification and death¶
pm_warn¶
instance or export
() pm_warn()
DESCRIPTION:
pm_notify¶
instance or export
() pm_notify()
DESCRIPTION:
pm_exit¶
instance or export
() pm_exit(string msg[, int exit_status])
DESCRIPTION:
pm_abort¶
instance or export
() pm_abort(string msg[, int exit_status])
DESCRIPTION:
BUGS¶
No known bugs, but this does not mean no bugs exist.
SEE ALSO¶
FCGI.
MAINTAINER¶
Gareth Kirwan <gbjk@thermeon.com>
AUTHOR¶
James E Jurach Jr.
COPYRIGHT¶
FCGI-ProcManager - A Perl FCGI Process Manager
Copyright (c) 2000, FundsXpress Financial Network, Inc.
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2 of the License, or (at your option) any later version.
BECAUSE THIS LIBRARY IS LICENSED FREE OF CHARGE, THIS LIBRARY IS
BEING PROVIDED "AS IS WITH ALL FAULTS," WITHOUT ANY WARRANTIES
OF ANY KIND, EITHER EXPRESS OR IMPLIED, INCLUDING, WITHOUT
LIMITATION, ANY IMPLIED WARRANTIES OF TITLE, NONINFRINGEMENT,
MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, AND THE
ENTIRE RISK AS TO SATISFACTORY QUALITY, PERFORMANCE, ACCURACY,
AND EFFORT IS WITH THE YOU. See the GNU Lesser General Public
License for more details.
You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA