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

I wrote sample code of thread control using signaling as advised by monks. As below, but the thread didn't exit when Ctrl+c pressed: 
#/usr/bin/perl -w
use strict;
use warnings;
use threads;
use threads::shared;

my @thrList;
my $count=1;
share $count;

$SIG{INT} = \&catch_CtrlC;
&main;

sub main
{
    my $counter = 3;
    while($counter)
    {
        $counter--;
        my $thrHandle = threads->create(\&thrdfun);
        push @thrList, $thrHandle;    
    }
    print " waiting \n";
    foreach(@thrList){
        $_->join(); 
    }
}    

sub thrdfun 
{
    $SIG{INT} = \&trExit;
    print "thrdfun: $count \n";
    $count++;
    while(1){
    }
    exit;
}

sub trExit
{ 
    print " exit \n";
    threads->exit(); 
}

sub catch_CtrlC 
{
    print " catch_CtrlC \n";
    foreach(@thrList){
        $_->kill("INT"); 
    }
    exit;
}

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In my plan, catch_CtrlC will first receive the signal and forward it to all thread one by one. For every thread, the trExit will do sth. and exit. I guess I'm using in a wrong way, righ?

Replies are listed 'Best First'.
Re: about THREAD SIGNALLING
by Khen1950fx (Canon) on Apr 23, 2013 at 06:26 UTC
    I believe you were looking for this: 
    #/usr/bin/perl 

use strict;
use warnings;
use threads;
use threads::shared;

my @thrList;
my $count = 1;
share $count;

my $counter = 3;

while($counter) {
     $counter--;
     my $thrHandle = threads->create(\&thrdfun);
     push @thrList, $thrHandle;    
}

foreach(@thrList){
     $_->join(); 
    }    

sub thrdfun {
    sub catch_CtrlC {
        $SIG{'INT'} = threads->kill('TERM');
    }
    
    $SIG{INT} = \&catchCtrlC;
     print "thrdfun: $count \n";
     $count++;
     while(1){
         ();
     }
     exit;
}

    [download]
[reply]
[d/l]
      OK. I'd like to find out why my code doesn't work. I found $SIG{'INT'} = threads->kill('TERM');changed to 
      threads->kill('TERM');

      [download]
      still works.

      Then I made a little more change to you code as:

      #/usr/bin/perl 

use strict;
use warnings;
use threads;
use threads::shared;
$SIG{INT} = \&catchCtrlC;
my @thrList;
my $count = 1;
share $count;

my $counter = 3;

while($counter) {
     $counter--;
     my $thrHandle = threads->create(\&thrdfun);
     push @thrList, $thrHandle;    
}

foreach(@thrList){
     $_->join(); 
    }   
    
sub catch_CtrlC {
        foreach(@thrList){
            $_->kill('TERM'); 
        }         
    }

sub thrdfun {    
     print "thrdfun: $count \n";
     $count++;
     while(1){
         ();
     }
     exit;
}

      [download]

      It doesn't work. Could you tell me why?

[reply]
[d/l]
[select]
        Just remember that sub catch_CtrlC {} and SIG{'INT'} = \&catch_CtrlC; must both be included in each thread that you want to SIGINT out of. 
        #/usr/bin/perl

use strict;
use warnings;
use threads;
use threads::shared;

my @thrList;
my $count = 1;
share $count;

my $counter = 3;

while ($counter) {
    $counter--;
    my $thrHandle = threads->create( \&thrdfun );
    push @thrList, $thrHandle;
}

foreach (@thrList) {
    $_->join();
}

sub thrdfun {

    sub catch_CtrlC {
        $_->kill('TERM');
    }

    $SIG{'INT'} = \&catch_CtrlC;
    print "thrdfun: $count \n";
    $count++;
    while (1) {
        ();
    }
    exit;
}

        [download]
[reply]
[d/l]
[select]
        What's more, can catch_CtrlC gets parameters? Why below little change, adding a print in catch_CtrlC doesn't print anything(see line print "counter: $counter \n"; )? 
        #/usr/bin/perl 

use strict;
use warnings;
use threads;
use threads::shared;

my @thrList;
my $count = 1;
share $count;

my $counter = 3;

while($counter) {
     $counter--;
     my $thrHandle = threads->create(\&thrdfun);
     push @thrList, $thrHandle;    
}

foreach(@thrList){
     $_->join(); 
    }    

sub thrdfun {
    sub catch_CtrlC {            
        print "counter: $counter \n";
        $SIG{'INT'} = threads->kill('TERM');
    }
    
    $SIG{INT} = \&catchCtrlC;
     print "thrdfun: $count \n";
     $count++;
     while(1){
         ();
     }
     exit;
}

        [download]
[reply]
[d/l]
[select]

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