As a (probably not very efficient) option, you can consider to coordinate
the different processes through a database, something like:
use Mojolicious::Lite;
use Mojo::IOLoop;
use Mojo::Pg;
helper pg => sub { state $pg = Mojo::Pg->new("postgresql:///test") };
app->pg->migrations->from_data->migrate;
app->log->path('ten_seconds.log');
Mojo::IOLoop->recurring(
1 => sub {
my $db = app->pg->db;
my $ctime = int(time);
$db->update_p(
'laststamp' => {ltime => $ctime + 10, pid => $$},
{ltime => {'<=', $ctime}}, {returning => 'ltime'}
)->then(
sub {
my $res = shift->hashes;
if ($res->first) {
# do some actual work here
app->log->info(sprintf "Modified by: pid %i, time up to: %i",
$$, $res->first->{ltime});
}
}
)->catch(
sub {
my $err = shift;
app->log->error(sprintf "Error: %s, pid: %i, time: %i", $err, $$, time);
}
);
}
);
get '/' => sub {
my $c = shift;
my $db = $c->pg->db;
$db->select_p(laststamp => undef)->then(
sub {
my $res = shift->hashes;
$c->render(
text => sprintf('Last modified by pid %i, up to %i',
@{$res->first}{qw(pid ltime)})
);
}
);
};
app->start;
__DATA__
@@ migrations
-- 1 up
create table laststamp (ltime integer, pid integer);
insert into laststamp (ltime, pid) values (0, 0);
-- 1 down
drop table laststamp;
It works because the sql update acts as a semaphore mechanism among the
processes, as the one that is able to update the database will atomically
update the ltime field by 10 seconds.
Please note that Mojolicious and Mojo::Pg should be in their last versions
(7.57 & 4.03) or at least a recent version that supported promises.
Hope it helps,
BR,
Daniel
El miércoles, 22 de noviembre de 2017, 0:30:27 (UTC-3), Dan Book escribió:
>
> If you add a recurring timer in startup it will execute in each worker
> process that is forked. You might consider having a separate process
> (possibly with a command for your application to spawn it) that just does
> this recurring work.
>
> -Dan
>
> On Tue, Nov 21, 2017 at 9:40 PM, Nancy Li <[email protected]
> <javascript:>> wrote:
>
>> OK. i managed to replicate the issue in dev. So it was actually caused by
>> using hypnotoad in production. I was using morbo in dev which probably only
>> had 1 thread and production might have 4 thread.
>>
>> I'm open for suggestions to tackle this issue though. This is my first
>> time using IOLoop and any advice is highly appreciated.
>>
>>
>> On Wednesday, November 22, 2017 at 12:49:37 PM UTC+11, Nancy Li wrote:
>>>
>>> * Mojolicious version: 7.39
>>> * Perl version: v5.24.9
>>> * Operating system: Linux AND 2.6.32-504.23.4.el6.x86_64
>>>
>>> ### Steps to reproduce the behavior
>>> I'm using Mojo::IOLoop->recurring to schedule a HTTP get request every
>>> 10s. However, from the log file, it seems the IOLoop is starting more than
>>> 1 job at the same time. Sometimes, there are 2 or 3 or 4 jobs running at
>>> the same time.
>>>
>>> Code:
>>> ```
>>> Mojo::IOLoop->recurring(
>>> 10 => sub {
>>> my $task = 'pull_reservation';
>>> my $backend = $self->minion->backend;
>>>
>>> my $inactive_batch
>>> = $backend->list_jobs( 0, -1, { state => 'inactive',
>>> task => $task, queue => 'default' } );
>>> my $active_batch = $backend->list_jobs( 0, -1, { state =>
>>> 'active', task => $task, queue => 'default' } );
>>>
>>> if ( ( !@$inactive_batch ) && ( !@$active_batch ) ) {
>>> $self->minion->enqueue( $task => [], { priority => 1 } );
>>> }
>>>
>>> }
>>> );
>>> ```
>>>
>>> ### Expected behavior
>>> IOLoop should only be starting one job at the time.
>>>
>>> ### Actual behavior
>>> IOLoop somestimes start more than 1 job. From the log file, it is
>>> starting 2 -4 jobs.
>>>
>>> ###Content from log file:
>>> ```
>>> [Wed Nov 22 11:02:35 2017] [info] job completed with 0 reservations
>>> with job_id 244828 .
>>> [Wed Nov 22 11:02:35 2017] [info] job completed with 0 reservations
>>> with job_id 244827 .
>>> [Wed Nov 22 11:02:35 2017] [info] job completed with 0 reservations
>>> with job_id 244829 .
>>> [Wed Nov 22 11:02:42 2017] [info] job completed with 0 reservations
>>> with job_id 244833 .
>>> [Wed Nov 22 11:02:42 2017] [info] job completed with 0 reservations
>>> with job_id 244832 .
>>> [Wed Nov 22 11:02:42 2017] [info] job completed with 0 reservations
>>> with job_id 244831 .
>>> [Wed Nov 22 11:02:42 2017] [info] job completed with 0 reservations
>>> with job_id 244830 .
>>> [Wed Nov 22 11:02:54 2017] [info] job completed with 0 reservations
>>> with job_id 244836 .
>>> [Wed Nov 22 11:02:54 2017] [info] job completed with 0 reservations
>>> with job_id 244834 .
>>> ```
>>>
>>> I've also checked the details of each parallel job, they have exactly
>>> the same create time.
>>>
>>> ```
>>> ./script/app.pl minion job 285950
>>> {
>>> "args" => [],
>>> "attempts" => 1,
>>> "children" => [],
>>> "created" => "2017-11-22T01:25:39Z",
>>> "delayed" => "2017-11-22T01:25:39Z",
>>> "finished" => "2017-11-22T01:25:44Z",
>>> "id" => 285950,
>>> "notes" => {},
>>> "parents" => [],
>>> "priority" => 1,
>>> "queue" => "default",
>>> "result" => {
>>> "uuid" => 246109
>>> },
>>> "retried" => undef,
>>> "retries" => 0,
>>> "started" => "2017-11-22T01:25:43Z",
>>> "state" => "finished",
>>> "task" => "pull_reservation",
>>> "worker" => 157
>>> }
>>> ./script/app.pl minion job 285951
>>> {
>>> "args" => [],
>>> "attempts" => 1,
>>> "children" => [],
>>> "created" => "2017-11-22T01:25:39Z",
>>> "delayed" => "2017-11-22T01:25:39Z",
>>> "finished" => "2017-11-22T01:25:44Z",
>>> "id" => 285951,
>>> "notes" => {},
>>> "parents" => [],
>>> "priority" => 1,
>>> "queue" => "default",
>>> "result" => {
>>> "uuid" => 246112
>>> },
>>> "retried" => undef,
>>> "retries" => 0,
>>> "started" => "2017-11-22T01:25:43Z",
>>> "state" => "finished",
>>> "task" => "pull_reservation",
>>> "worker" => 157
>>> }
>>>
>>> ```
>>> While doing trouble shooting, I started using IOLoop->singleton, but it
>>> didn't solve this problem :(
>>>
>>> Any pointers are highly appreciated.
>>>
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>
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