Beefy Boxes and Bandwidth Generously Provided by pair Networks
Don't ask to ask, just ask
 
PerlMonks  

Sending signals to threads that trying to join

by mojo2405 (Acolyte)
on Aug 22, 2013 at 14:49 UTC ( #1050536=perlquestion: print w/ replies, xml ) Need Help??
mojo2405 has asked for the wisdom of the Perl Monks concerning the following question:

Hi, So, I'm attaching my code. The code create 3 sons (with fork). Then each son create 3 grand sons (with thread). What I'm failing to do is to send to a son (started with fork) a USR1 signal , which will make all its grand sons to exit immediatly (and not wait to the grand sons to exit after they finish their work). I want to send the USR1 signal from outside to the son PID. I know there is a limitation and I might can not do that, but do other here another clean way to exit threads of the son immediatly when son gets USR1 signal ? Thanks ! Here is the code , the goal is to make the threads to exit while sleep function starting :
#!/usr/bin/env perl use threads; ##kill -10 handle $SIG{USR1}=\&usr_kill_handler; my @sons = ("Son1","Son2","Son3"); my @childs = (); #Start fork foreach my $son (@sons){ my $pid = fork(); if ($pid) { # parent push(@childs, $pid); }elsif($pid == 0) { # child my $results = new testProcess($son); exit 0; }else { print "\nerror : couldnt fork: $!\n"; exit 1; } } #Wait for to end foreach my $child (@childs) { my $tmp = waitpid($child, 0); print "\ninfo : done with pid $tmp\n"; } sub usr_kill_handler{ #Send SIGUSR1 to all childs (started with fork) kill SIGUSR1 => @childs; print "\n\n Stoped due to user request!\n\n"; #Wait to all childs to exit foreach my $child (@childs) { my $tmp = waitpid($child, 0); print "\ndone with pid $tmp\n"; } # After all child ended kill father exit 1; } package testProcess; sub new{ my $class = shift; my ($son) = @_; ##kill -10 handle $SIG{USR1}=sub { print "\n Got signal to son $son with pid ".$$." \n"; threads->exit; }; print "\nSon $son with PID ".$$." Started\n"; my %hash_results = (); my @grand_sons = ("Grand son 1","Grand son 2","Grand son 3"); my @threads = (); #Start new thread foreach my $grand_son (@grand_sons){ my $t = threads->create (\&start_threads,$son,$grand_son); push(@threads,$t); } my $index=0; foreach my $thread (@threads) #wait for all threads untill the end + and insert results to hash { $hash_results{$index}=$thread->join; $index++; } print "\nSon $son with PID ".$$." Finished\n"; } sub start_threads{ my ($son,$grand_son) = @_; print "\nSon $son grand son $grand_son started\n"; my $random_number = int(rand(100)); my $msg = "Son $son grand son $grand_son returns random number $ra +ndom_number"; print "\n$msg\n"; sleep 100; return $random_number; } 1;

Comment on Sending signals to threads that trying to join
Download Code
Re: Sending signals to threads that trying to join
by vsespb (Hermit) on Aug 22, 2013 at 19:26 UTC
    Seems problem that join() call blocks signals (i.e. signal will arrive after join() finished).

    some related links:

    http://stackoverflow.com/questions/7534566/perl-trapping-ctrl-c-with-threads-in-bash

    http://cpanforum.com/threads/2548
Re: Sending signals to threads that trying to join
by afoken (Parson) on Aug 24, 2013 at 08:43 UTC

    Threads and signals don't mix well. It highly depends on the operating system which thread will receive signals. In the worst case, signals are delivered to a randomly choosen thread. Use the search function to see some other discussions.

    Alexander

    --
    Today I will gladly share my knowledge and experience, for there are no sweeter words than "I told you so". ;-)

Log In?
Username:
Password:

What's my password?
Create A New User
Node Status?
node history
Node Type: perlquestion [id://1050536]
Approved by kcott
help
Chatterbox?
and the web crawler heard nothing...

How do I use this? | Other CB clients
Other Users?
Others meditating upon the Monastery: (13)
As of 2014-12-18 20:00 GMT
Sections?
Information?
Find Nodes?
Leftovers?
    Voting Booth?

    Is guessing a good strategy for surviving in the IT business?





    Results (61 votes), past polls