readline挂在手动管道上()

# magic-fork.pl
if (open my $fh, '-|') { # fork self, make new fd for reading, attach child STDOUT to it
    STDOUT->say('parent getpid: ', $$);
    STDOUT->say('parent STDOUT->fileno: ', STDOUT->fileno);
    STDOUT->say('parent $fh->fileno: ', $fh->fileno);
    while (my $line = $fh->getline) {
        STDOUT->print('parent readline from child: ', $line);
    }
} else {
    STDOUT->say('child getpid: ', $$);
    STDOUT->say('child STDOUT->fileno: ', STDOUT->fileno);
}

# plain-fork.pl
pipe my $r, my $w;
if (fork) {
    STDOUT->say('parent getpid: ', $$);
    STDOUT->say('parent STDOUT->fileno: ', STDOUT->fileno);
    STDOUT->say('parent $r->fileno: ', $r->fileno);
    STDOUT->say('parent $w->fileno: ', $w->fileno);
    while (my $line = $r->getline) {
        STDOUT->print('parent readline from child: ', $line);
    }
} else {
    $w->say('child getpid: ', $$);
    $w->say('child $r->fileno: ', $r->fileno);
    $w->say('child $w->fileno: ', $w->fileno);
    $w->say('child STDOUT->fileno: ', STDOUT->fileno);
}

此程序意外挂起在循环中。

我试着没有用:

• 拨打$w->自动冲洗(1)
• 显式退出
• 检查strace-ff以查看是否错过了一个重要的系统调用