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Home: Perl Programming Help: Intermediate:
killing threads inside forks


New User

Jul 31, 2013, 5:02 AM

Post #1 of 2 (1353 views)
killing threads inside forks Can't Post

Hi, I have a code now that starts fork (with few childs). Each child runs few threads. What I want to do is to - catch a ctrl + c from user by the parent (this part is working for me) , send a signal to the children that kills immediatly the threads and do some more code (write to DB, etc..) - this part is half working for me. the part that working is the children actually catches the signal ( I'm using USR1 signal ) , and hte part that doesnt work for me - us that it catches it only when the threads end. if not threads run in the fork children - the form catches the signal immediatly. Any ideas guys ? this is how I send the USR1 to children :

kill USR1 => (keys %framework_child_procs);  

thanks ! 

New User

Jul 31, 2013, 7:46 AM

Post #2 of 2 (1350 views)
Re: [mojo2405] killing threads inside forks [In reply to] Can't Post

I better be more clearer and show some code..

So this is the father starting his children :

#Start fork
foreach my $xml_obj (@{$xml_ojects_ref}){
my $pid = fork();
if ($pid) {
# parent
push(@childs, $pid);
$framework_child_procs{$pid} = 1;
}elsif($pid == 0) {
# child
my $results = new testProcess($xml_obj,$fatherSN); #Test process is a new run
exit 0;
}else {
print ,"couldnt fork: $!";
exit 1;

#Wait for to end
foreach my $child (@childs) {
my $tmp = waitpid($child, 0);
print "done with pid $tmp";


This is the code (inside the father class) , which handles the CTRL+C:


sub ctrl_c_handler
my @procs = keys (%{fatherProcess::framework_child_procs});
kill SIGUSR1 => @procs;

foreach my $child (@procs) {
my $tmp = waitpid($child, 0);

This is a code inside a child (this is how I start the threads inside a child actually):

my $t = threads->new (sub{
local $SIG{'USR1'}=sub {threads->exit();};

my $result = $t->join();

Now the signal (CTRL+C) comes from the user / CLI , then it catched by the father (going to ctrl_c_handler function) , and then ctrl_c_handler function suppose to send the USR1 signal to the threads - but the thread doesn't catch it.

In addition - in the child (testProcess), before starting the thread , I have another USR1 handler , which caught - only after the thread is ending.

I think your solution is not suitable here..

please help :)


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