Hi Monks,
I am testing a small program to understand how interrupt handling works in a program that uses threads and the "expect.pm" module. With this code, I am calling a shell script (which basically just sleeps for X seconds - to simulate some other actual program I intend to use my Perl code for).

Lets assume my code does a bit of critical stuff and a bunch of other non critical stuff. When I get a Ctrl C while the critical stuff is running, I want the program to wait until it completes processing and then quit. Also, when it gets a Ctrl C while doing the non critical stuff, it can go ahead and abort right away (of course after performing cleanup and other housekeeping stuff)

Here's my code that does this work:

#!/usr/bin/perl
use strict;
#use warnings;
use Term::ReadKey;
use Text::Wrap;
use Term::Prompt;
use Expect;
use threads;
use threads::shared;
use Term::ANSIColor;
use File::Path;
use HTML::Entities;
use MIME::QuotedPrint;
use MIME::Base64;
use MIME::Lite;
use Date::Calc qw(Delta_DHMS);

my $pass = "<password>";
my $User = "<username>";

$SIG{'INT' } = 'interrupt';  
$SIG{'QUIT'} = 'interrupt';
$SIG{'HUP' } = 'interrupt';  
$SIG{'TRAP'} = 'interrupt';
$SIG{'ABRT'} = 'interrupt';  
$SIG{'STOP'} = 'interrupt';

my $sshAuth = Expect->spawn("ssh $User\@hostname");
$sshAuth->log_stdout(0);

my $thr1 = threads->create('thread1',$sshAuth);
$thr1->join();

sub thread1
{
    
    my $sshAuth = shift;
    our $sleepFlag = '';
    
    $sshAuth->expect(1000,    [qr/[Yy]es/     => sub {$sshAuth->send("
+yes\n");}],
                [qr/[Pp]assword\:\s/     => sub {$sshAuth->send("$pass
+\n");}]
                
            );
    $sshAuth->log_stdout(0);

    
    $sshAuth->expect(1000,    [qr/\$/ => sub {$sshAuth->send("\n");}])
+;
    $sshAuth->log_stdout(0);

    $sshAuth->expect(1000,    [qr/\$/ => sub {$sshAuth->send("cd Perl\
+/Test\n");}]);
    $sshAuth->log_stdout(0);

    ###### Here are the critical tasks that should not abort on Ctrl+C
+ #########
    our $sleepFlag = "true";
    $sshAuth->expect(1000,    [qr/\$/ => sub {$sshAuth->send("\.\/slee
+per\.sh\n");}]);
    $sshAuth->log_stdout(0);
    print "Entering Critical sleeping ... \n";

    $sshAuth->expect(1000,    [qr/\$[\s]*/     => sub {$sshAuth->send(
+"\n");}]);
    $sshAuth->log_stdout(0);

    print "Woke up \n";
    our $sleepFlag = "false";

    ###### I really dont mind if the stuff here terminates on Ctrl+C #
+########
    $sshAuth->expect(1000,    [qr/\$/ => sub {$sshAuth->send("\.\/slee
+per\.sh\n");}]);
    $sshAuth->log_stdout(0);
    print "Entering Non Critical sleeping ... \n";

    $sshAuth->expect(1000,    [qr/\$[\s]*/ => sub {$sshAuth->send("\n"
+);}]);
    $sshAuth->log_stdout(0);
    print "Woke up \n";

    $sshAuth->close();
}

sub interrupt
{
    our $sleepFlag:shared;
    
    print "$sleepFlag\n";
    print "Waiting for critical tasks to finish before terminating pro
+gram";
    while ($sleepFlag eq "true")
    {
        print ".";
        sleep(3);
    }
    print "\n\nNo critical tasks are running... it\'s safe to terminat
+e now...\n";
    print "Terminating Program!!!\n";
}

[download]

By the way, the sleeper.sh script, that is used to simulate a task that my script runs contains this:

sleep 60 ;

[download]

When I press Ctrl C while this code is running, nothing happens. As per my understanding, while in the critical execution phase, a Ctrl C should give me the message

Waiting for critical tasks to finish before terminating program

and while I press Ctrl C when the code is running in the non critical execution phase, it should print 

No critical tasks are running... it's safe to terminate now...
Terminating Program!!!

[download]

But as I see, nothing happens until the thread completes execution and is joined in the main thread. What am I doing wrong here?

In reply to Interrupt Handling - What am I doing wrong? by vishi

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