Update: Removing the shared hash code solves the hanging process problem, see below.

Unfortunately this, too, simply hangs on interrupt:

PID 28907
Forked worker in slot 2 with pid 28910 for chunk 1
Forked worker in slot 1 with pid 28909 for chunk 2
After 1: $VAR1 = {
          '00 28910' => '1491580974',
          '01 28909' => '1491580974'
        };

After 0: $VAR1 = {
          '00 28910' => '1491580974',
          '01 28909' => '1491580974'
        };

Forked worker in slot 1 with pid 28909 for chunk 3
Forked worker in slot 2 with pid 28910 for chunk 4
After 2: $VAR1 = {
          '00 28910' => '1491580974',
          '01 28909' => '1491580974',
          '02 28909' => '1491580975'
        };

After 3: $VAR1 = {
          '00 28910' => '1491580974',
          '01 28909' => '1491580974',
          '02 28909' => '1491580975',
          '03 28910' => '1491580975'
        };

^CHello from INT
Hello from INT
Hello from INT
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... hangs here ... all three processes alive:

pgr mce

nickt    28907       01:26 perl mce4.pl
nickt    28909       01:26 perl mce4.pl
nickt    28910       01:26 perl mce4.pl
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I am running on Debian, Perl 5.16.3, with the very latest MCE modules.

Thank you.

Update: Note that if I simply comment out all the shared hash code, the program can be interrupted and the processes do not hang, but the END block is never reached:

perl mce4.pl

PID 29593
Forked worker in slot 2 with pid 29596 for chunk 1
Forked worker in slot 1 with pid 29595 for chunk 2
Forked worker in slot 1 with pid 29595 for chunk 4
Forked worker in slot 2 with pid 29596 for chunk 3
^CHello from INT
Worker is ready to dump
Hello from INT
Parent is ready to dump
Hello from INT
Worker is ready to dump

## mce4.pl: caught signal (INT), exiting

Killed
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... above with this code:

use strict; use warnings; use feature 'say';
use Data::Dumper; ++$Data::Dumper::Sortkeys;
use MCE::Shared;
use MCE::Loop;
$|++;

my $pid = $$; say "PID $pid";
my $mutex = MCE::Mutex->new();

#tie my %hash, 'MCE::Shared', ();

$SIG{'INT'} = sub {
    my $signal = shift;
    say 'Hello from INT';
#    if ( tied(%hash)->len ) {
        (MCE->wid == 0) ? say 'Parent is ready to dump'
                        : say 'Worker is ready to dump';

#        say 'Dumping: ' . Dumper \%hash;
#        %hash = ();
#    }
    MCE::Signal::stop_and_exit($signal);
};

$SIG{'TERM'} = sub {
    my $signal = shift;
    say 'Hello from TERM';
    if (MCE->wid > 0) { # worker
        MCE->exit(0);
    } else { # parent
        say 'Parent is ready to dump';
#        say 'Dumping: ' . Dumper \%hash;
        MCE::Signal::stop_and_exit($signal);
    }
};

MCE::Loop->init( max_workers => 2, chunk_size => 1 );

mce_loop {
    my ( $mce, $chunk_ref, $chunk_id ) = @_;
    say sprintf 'Forked worker in slot %s with pid %s for chunk %s', M
+CE->wid, MCE->pid, $chunk_id;
    for ( @{ $chunk_ref } ) {
#        $hash{ sprintf '%.2d %s', $_, $$ } = time;
        $mutex->synchronize( sub {
#           say "After $_: " . Dumper \%hash;
        });
        sleep 1;
    }
} ( 0 .. 4 );

MCE::Loop->finish;

END {
    say sprintf '%s %s (%s) in END', $$, time, $$ == $pid ? 'Parent' :
+ 'Child';
    if ( MCE->wid == 0 or $$ == $pid ) {
        say "Parent is ready to dump";
#        say 'Dumping: ' . Dumper \%hash;
    }
}
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