perl中可以分叉的进程数是否有限制？

Question

我面临着一个奇怪的问题.分叉进程的增长不超过64.

sub create_process()
{
    my $child_pid;
    my @nsitr;

    my $i = 0;

    foreach my $domain (@domains)
    {
        @nsitr = @nameservers;
        open my $dnsfh, '>', $outputfile or die "Unable to open $outputfile - $!";
        foreach my $ns (@nameservers)
        {
            print "Forking child $i\n";
            defined($child_pid = fork() ) or (die "Unable to fork a new process" && next);
            $i++;
            if($child_pid == 0)
            {
                &resolve_dns($dnsfh, $domain, $ns);
                exit;
            }

        }
        close $dnsfh;
    }
}

产量

...
...
Forking child 60
Forking child 61
Forking child 62
Forking child 63
Forking child 64
Forking child 64
Forking child 64
Forking child 64
Forking child 64
...
...

Answer 1

Perl没有定义这样的限制,但大多数操作系统都这样做.用waitpid收获的孩子,或在类Unix系统中,你可以使用sigaction(从POSIX模块)忽略SIGCHLD与SA_NOCLDWAIT标志使系统自动获得孩子.(Linux碰巧让你省略SA_NOCLDWAIT,但无论如何你都应该使用它.)