davies has asked for the wisdom of the Perl Monks concerning the following question:

I am trying to get one of the examples from the official documentation working. I accept that putting code snippets together has problems, but I have tried lots of variants without success. The example is about 75% of the way through the document and starts with my $pool = AnyEvent::Fork. My current version of it is:

use strict;
use warnings;
use AnyEvent;
use AnyEvent::Fork;
use feature 'say'; 

package Some;
# Some::function might look like this - all parameters passed before f
+ork
# and after will be passed, in order, after the communications socket.
sub funct{
    my ($fh, $str1, $str2, $fh1, $fh2, $str3) = @_;
    print scalar <$fh>; # prints "hi #1\n" and "hi #2\n" in any order
}

package main;

my $pool = AnyEvent::Fork
             ->new
             ->send_arg ("str1", "str2")
;

for (1..2) {
    $pool
        ->fork
        ->send_arg ("str3")
        ->run ("Some::funct", sub {
            say 'Inside anonysub';
         });
}

say 'Outside pool loop';
AnyEvent->condvar->recv;

[download]

Thjis goes into an infinite loop after printing the output below:

Outside pool loop
Inside anonysub
Inside anonysub
Goto undefined subroutine &Some::funct at /usr/local/share/perl/5.24.1
+/AnyEvent/Fork/Serve.pm line 87.
Goto undefined subroutine &Some::funct at /usr/local/share/perl/5.24.1
+/AnyEvent/Fork/Serve.pm line 87.

[download]

I'm not worried about the infinite loop - at least not yet - but the inability to find a fully qualified sub (what the docs say is required) puzzles me. Could someone please give me a pointer?

Regards,

John Davies

Replies are listed 'Best First'.
Re: AnyEvent::Fork not working as expected
by jo37 (Curate) on Jun 28, 2021 at 20:12 UTC

    It looks like AnyEvent::Fork insists in require'ing a module. Separating the Some package into a .pm file makes the "undefined subroutine" go away, though it results in some "uninitialized value" errors. 

    use lib '.';
my $pool = AnyEvent::Fork
              ->new
              ->require("Some")
              ->send_arg ("str1", "str2")
;

    [download]

    Greetings,
    -jo

    $gryYup$d0ylprbpriprrYpkJl2xyl~rzg??P~5lp2hyl0p$
[reply]
[d/l]
[select]
Re: AnyEvent::Fork not working as expected
by Aldebaran (Curate) on Jul 01, 2021 at 06:07 UTC
    I have tried lots of variants without success.

    So have I with fork scripts, and I haven't come up with anything satifactory. I received this warning for several of M Lehmann's modules including this one:

    *** The stability canary says: (nothing, it was driven away by harsh w
+eather)
***
*** It seems you are running perl version 5.030000, likely the "offici
+al" or
*** "standard" version. While there is nothing wrong with doing that,
*** standard perl versions 5.022 and up are not supported by JSON::XS.
*** While this might be fatal, it might also be all right - if you run
+ into
*** problems, you might want to downgrade your perl or switch to the
*** stability branch.
***
*** If everything works fine, you can ignore this message.

    [download]

    I tried to let it run its course but eventually control-c'ed and q'ed my way out of it. I'll just chalk it up as one of many failed attempts to use some type of fork in perl. Instead of trying again, I should probably just accept that perl is uniprocess by design and not use a hammer as a screwdriver.

[reply]
[d/l]
      The easiest and recommended solution is not to use modules by the mentioned author. For the mentioned module, JSON::XS, an alternative exists: Cpanel::JSON::XS.

      map{substr$_->[0],$_->[1]||0,1}[\*||{},3],[[]],[ref qr-1,-,-1],[{}],[sub{}^*ARGV,3]
[reply]
[d/l]

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