perl - 使用选择轮询连接-TCP服务器

Question

use strict; use warnings;
use IO::Socket;
use IO::Select;
my $read_select  = IO::Select->new();
my $write_select = IO::Select->new();

my $socket = IO::Socket::INET->new(
            LocalHost => '127.0.0.1',
            LocalPort => '5556',
            Proto => 'tcp',
            Listen => 50,
            Reuse => 1,
 ) or die "Could not create socket: $!";

 print "Socket Created . Waiting for connection ...\n";

 ## poll to accept new connection or to receive data from a connection

 $read_select->add($socket);

 print "Added socket to read list ";
 my $reade;
 my $newconn;
 my @read;
 my @write;
 while(1) {
    @read = $read_select->can_read();

    foreach my $reade(@read) {
            if($reade == $socket) {
                    print "New conn received";
                    my $newconn = $reade->accept();
                    $write_select->add($newconn);

            }
            else {
                    print "data received";
            }
    }
 }
 @write = $write_select->can_write();

 foreach my $write(@write) {
    $write->send("got ur data");
 }

我正在尝试使用select语句轮询连接。为什么如果我使用无限循环，则不接受任何连接。没有while(1)即可正常工作

Answer 1

我认为您在这里被I/O缓冲所困扰。 Perl缓冲所有输入和输出。在收到整行之前，它通常不会打印到终端上。

您的代码可能与while(1)一起使用，但是您看不到调试打印语句的输出，因为终端的输出正在缓冲中。一旦您进入第二次循环，$read_select->can_read()就会永远阻塞，因此您永远不会看到print语句的输出。

您可能只需在每个print语句的末尾添加\n即可解决此问题。另一种选择是设置$| = 1;。这将禁用缓冲。有关缓冲的更多信息，请参见perlvar's discussion of $| 。