UserAgent: memory leak

[dpanech]

• Mojolicious version: 9.31
• Perl version: v5.16.3
• Operating system: CentOS 7

Steps to reproduce the behavior

UserAgent leaks, here's a minimal example:

#!/usr/bin/perl

use warnings;
use strict;
use Mojo::IOLoop;
use Mojo::UserAgent;

# IOLoop
my $IOLOOP = Mojo::IOLoop->singleton;

# Create UA
my $UA =  Mojo::UserAgent->new;
$UA->ioloop ($IOLOOP);  # not sure if this is necessary

# Make a client request
my $COUNT = 0;
sub ua_test_1($$) {
    my ($host, $port) = @_;

    my $url = "http://$host:$port/";
    ++$COUNT;
    $UA->get_p ($url)
        ->catch (sub {
            print STDERR $host, ':', $port, ': ', @_, " [COUNT=$COUNT]\n"
        })
        ->finally (sub {
            $IOLOOP->next_tick (sub { ua_test_1 ($host, $port) });
            --$COUNT;
        });
}

ua_test_1 ("localhost", 1234);  # some unused port for "connection refused"

print "PID=$$\n";
print "Press ENTER to start\n";
readline();
$IOLOOP->start();

Expected behavior

Memory usage should remain steady while this script is running.

Actual behavior

Memory reported by top (the VIRT column) steadily increases by approx 20 KiB per second.

Note that the example above doesn't involve self-referencing closures - AFAICT - so it can't be that.

[kraih]

Not a leak, you're just not giving the event loop any time to do actual work.

[dpanech]

Sorry, what work? I'm scheduling next tick after the request has completed, no ?

[dpanech]

I just tried replacing next_tick with

$IOLOOP->timer (0.01 => sub { ua_test_1 ($host, $port) });

Memory usage still increases, but more slowly.

[dpanech]

Same with timer (0.1 => ...

[dpanech]

Upgraded to perl 5.24 and it's not happening anymore!

[kraih]

Interesting, i've only tested it on Perl 5.36.