Question

我正在编写一个管理多重过程的程序。这就是我所做的，它的工作很棒！但现在，我想从子进程发送消息到父进程，反之亦然（从父进程到子进程），你知道最好的方法吗？你知道我所做的是否是我想要的正确方法（从子进程发送消息，信号或共享内存到父进程，反之亦然）？

提前致谢!!


#!/usr/bin/perl -w
use strict;
use warnings;

main(@ARGV);

sub main{
    my $num = 3; #this may change in the future (it would be dynamic)
    my @parts = (1,4,9,17,23,31,46,50);
    my @childs = ();

    while(scalar(@parts)>0 || scalar(@childs)>0){
        if(scalar(@parts)>0){
            my $start = scalar(@childs) + 1;
            for($start..$num){
                my $partId = pop(@parts);
                my $pid = fork();
                if ($pid) {
                    print "Im going to wait (Im the parent); my child is: $pid. The part Im going to use is: $partId \n";
                    push(@childs, $pid);
                } 
                elsif ($pid == 0) {
                    my $slp = 5 * $_;
                    print "$_ : Im going to execute my code (Im a child) and Im going to wait like $slp seconds. The part Im going to use is: $partId\n";
                    sleep $slp;
                    print "$_ : I finished my sleep\n";
                    exit($slp);
                } 
                else{
                    die "couldn’t fork: $!\n";
                }   
            }
        }

        print "before ret\n";
        my $ret = wait();
        print "after ret. The pid=$ret\n";

        my $index = 0;
        for my $value (@childs){
            if($value == $ret) {
                splice @childs, $index, 1;
                last;
            }
            $index++;
        }
    }

}

Answer 1

使用kill。如果在fork之前在父级中设置变量，则不需要任何外部选项。

my $parent_pid = $$; # Keep a reference to the parent

my $pid = fork();
if ($pid) {
    print "Im going to wait (Im the parent); 
    my child is: $pid. The part Im going to use is: $partId \n";
    push(@childs, $pid);
} 
elsif ($pid == 0) {
   my $slp = 5 * $_;
   print "$_ : Im going to execute my code (Im a child) and Im going to wait like $slp seconds. The part Im going to use is: $partId\n";
   sleep $slp;
   print "$_ : I finished my sleep\n";

   kill 20, $parent_pid # Send a signal to the parent, 20 is SIGCHLD

   exit($slp);
}

有关kill调用的更多详细信息，请参阅perldoc -f kill 如果您需要做更复杂的事情，另一个选择是使用POE

Answer 2

Forks::Super具有良好的接口，用于在父进程和子进程之间传递消息（进程间通信）。使用此接口，您可以将消息传递给子节点的STDIN，并从子节点的STDOUT和STDERR句柄中读取消息。

use Forks::Super;

# set up channels to child's STDIN/STDOUT/STDERR with blocking I/O
my $pid = fork { child_fh => 'all,block' };

if ($pid) { # parent
    $pid->write_stdin("Hello world\n");
    my $msg_from_child = $pid->read_stdout(); # <-- "HELLO WORLD\n"
    print "Message from child to parent: $msg_from_child";
} 
elsif (defined($pid) && $pid == 0) { # child
    sleep 1;
    my $msg_from_parent = <STDIN>;            # <-- "Hello world\n"
    my $output = uc $msg_from_parent;
    print $output;
    exit 0;
} 
else{
    die "couldn’t fork: $!\n";
}

如何从父进程向子进程发送消息（或信号），反之亦然？

2 个答案: