Stop a thread when another thread stops in Perl - linux

Question

Hi I am trying to stop or kill the thread $t2 when $t1 stops. Here is the code:
#!/usr/local/bin/perl
use strict;
use warnings;
use threads;
use threads::shared;
use Time::HiRes qw( sleep );
print "Starting main program\n";
my #threads;
my $t1 = threads->new(\&c1);
my $t2 = threads->new(\&progress);
#my $t2 = threads->new(\&c2);
push(#threads,$t1);
push(#threads,$t2);
my $ret1 = $t1->join();
print "Thread returned: $ret1\n";
$t2->join();
if (!($t1->is_running()))
{
$t2->exit();
}
print "End of main program\n";
sub c1
{
print "Inside thread 1\n";
sleep 5;
return 245;
}
sub c2
{
print "Inside thread 2\n";
}
sub progress
{
$| = 1; # Disable buffering on STDOUT.
my $BACKSPACE = chr(0x08);
my #seq = qw( | / - \ );
for (;;) {
print $seq[0];
push #seq, shift #seq;
sleep 0.200;
print $BACKSPACE;
}
print "$BACKSPACE $BACKSPACE";
}
But thread $t2 continues running. Please help me out with this.
How to kill thread $t2.
I am confused with join(), detach(), exit()

Answer 1

You can't call exit on thread instance $t2->exit() and module warns you about that,
perl -Mthreads -we '$_->exit(3) and $_->join for async {sleep 4}'
Usage: threads->exit(status) at -e line 1
Perl exited with active threads:
1 running and unjoined
0 finished and unjoined
0 running and detached
However, you can send a signal to thread (check signal list)
# Send a signal to a thread
$thr->kill('SIGUSR1');

Answer 2

You can use a shared variable:
use threads::shared;
my $done : shared;
$done = 0;
my $t1 = threads->new( sub { c1(); $done = 1;} );
And in the progress function:
# ...
for (;!$done;) {
# ....