NAME
Gearman::Driver - Manages Gearman workers
SYNOPSIS
package My::Workers::One;
use base qw(Gearman::Driver::Worker);
use Moose;
# this method will be registered with gearmand as 'My::Workers::One::scale_image'
sub scale_image : Job {
my ( $self, $job, $workload ) = @_;
# do something
}
# this method will be registered with gearmand as 'My::Workers::One::do_something_else'
sub do_something_else : Job : MinChilds(2) : MaxChilds(15) {
my ( $self, $job, $workload ) = @_;
# do something
}
# this method wont be registered with gearmand at all
sub do_something_internal {
my ( $self, $job, $workload ) = @_;
# do something
}
1;
package My::Workers::Two;
use base qw(Gearman::Driver::Worker);
use Moose;
# this method will be registered with gearmand as 'My::Workers::Two::scale_image'
sub scale_image : Job {
my ( $self, $job, $workload ) = @_;
# do something
}
1;
package main;
use Gearman::Driver;
my $driver = Gearman::Driver->new(
namespaces => [qw(My::Workers)],
server => 'localhost:4730,otherhost:4731',
interval => 60,
);
$driver->run;DESCRIPTION
Having hundreds of Gearman workers running in separate processes can consume a lot of RAM. Often many of these workers share the same code/objects, like the database layer using DBIx::Class for example. This is where Gearman::Driver comes in handy:
You write some base class which inherits from Gearman::Driver::Worker. Your base class loads your database layer for example. Each of your worker classes inherit from that base class. In the worker classes you can register single methods as jobs with gearmand. It's even possible to control how many workers doing that job/method in parallel. And this is the point where you'll save some RAM: Instead of starting each worker in a separate process Gearman::Driver will fork each worker from the main process. This will take advantage of copy-on-write on Linux and save some RAM.
There's only one mandatory parameter which has to be set when calling the constructor: namespaces
use Gearman::Driver;
my $driver = Gearman::Driver->new( namespaces => [qw(My::Workers)] );See also: namespaces. If you do not set server (gearmand) attribute the default will be used: localhost:4730
Each module found in your namespaces will be loaded and introspected, looking for methods having the 'Job' attribute set:
package My::Workers::ONE;
sub scale_image : Job {
my ( $self, $job, $workload ) = @_;
# do something
}This method will be registered as job function with gearmand, verify it by doing:
plu@mbp ~$ telnet localhost 4730
Trying ::1...
Connected to localhost.
Escape character is '^]'.
status
My::Workers::ONE::scale_image 0 0 1
.
^]
telnet> Connection closed.If you dont like to use the full package name you can also specify a custom prefix:
package My::Workers::ONE;
sub prefix { 'foo_bar_' }
sub scale_image : Job {
my ( $self, $job, $workload ) = @_;
# do something
}This would register 'foo_bar_scale_image' with gearmand.
See also: prefix
ATTRIBUTES
namespaces
Will be passed to Module::Find useall method to load worker modules. Each one of those modules has to be inherited from Gearman::Driver::Worker or a subclass of it. It's also possible to use the full package name to load a single module/file. There is also a method get_namespaces which returns a sorted list of all namespaces.
isa:
ArrayRefrequired:
True
server
A list of Gearman servers the workers should connect to. The format for the server list is: host[:port][,host[:port]]
See also: Gearman::XS
default:
localhost:4730isa:
Str
interval
Each n seconds Net::Telnet::Gearman is used in Gearman::Driver::Observer to check status of free/running/busy workers on gearmand. This is used to fork more workers depending on the queue size and the MinChilds/MaxChilds attribute of the job method. See also: Gearman::Driver::Worker
default:
5isa:
Int
logfile
Path to logfile.
isa:
Strdefault:
gearman_driver.log
loglayout
See also Log::Log4perl.
isa:
Strdefault:
[%d] %p %m%n
loglevel
See also Log::Log4perl.
isa:
Strdefault:
INFO
lib
This is just for convenience to extend @INC from command line using gearman_driver.pl:
gearman_driver.pl --lib ./lib --lib /custom/lib --namespaces My::Workersisa:
Str
unknown_job_callback
Whenever Gearman::Driver::Observer sees a job that isnt handled it will call this CodeRef, passing following arguments:
$driver$status
my $driver = Gearman::Driver->new(
namespaces => [qw(My::Workers)],
unknown_job_callback => sub {
my ( $driver, $status ) = @_;
# notify nagios here for example
}
);$status might look like:
$VAR1 = {
'busy' => 0,
'free' => 0,
'name' => 'GDExamples::Sleeper::unknown_job',
'queue' => 6,
'running' => 0
};INTERNAL ATTRIBUTES
This might be interesting for subclassing Gearman::Driver.
modules
Every worker module loaded by Module::Find will be added to this list. There are also two methods: get_modules and has_modules.
isa:
ArrayRefreadonly:
True
jobs
Stores all Gearman::Driver::Job instances. The key is the name the job gets registered with gearmand. There are also two methods: get_job and has_job.
Example:
{
'My::Workers::ONE::scale_image' => bless( {...}, 'Gearman::Driver::Job' ),
'My::Workers::ONE::do_something_else' => bless( {...}, 'Gearman::Driver::Job' ),
'My::Workers::TWO::scale_image' => bless( {...}, 'Gearman::Driver::Job' ),
}isa:
HashRefreadonly:
True
observer
Instance of Gearman::Driver::Observer.
isa:
Gearman::Driver::Observerreadonly:
True
METHODS
Every method except run might only be interesting for people subclassing Gearman::Driver.
run
This must be called after the Gearman::Driver object is instantiated.
get_namespaces
Returns a sorted list of namespaces.
get_modules
Returns a sorted list of modules.
has_modules
Returns the count of modules.
has_job
Params: $name
Returns true/false if the job exists.
get_job
Params: $name
Returns the job instance.
AUTHOR
Johannes Plunien <plu@cpan.org>
COPYRIGHT AND LICENSE
Copyright 2009 by Johannes Plunien
This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.