PHP套接字脚本导致很多很长的CLOSE_WAIT套接字连接

Question

我有一个PHP脚本（我可以在线找到）无限期地监听一个端口，如果有连接到这个端口，它将建立一个TCP connection。然而，当我运行这个脚本并且有很多连接（大约500）时，连接的数量会增加。在此状态下连接的远程设备无法再次连接，因为CLOSE_WAIT未终止。

// port info 
$host = "0.0.0.0"; 
$port = 10260; 
$pos = 1; 

// don't timeout! 
set_time_limit(0); 
record("START"); 

$sock = socket_create(AF_INET, SOCK_STREAM, 0); 
$timeout = array('sec'=>3000,'usec'=>0); 
$try = socket_set_option($sock,SOL_SOCKET,SO_RCVTIMEO,$timeout); 

// Bind the socket to the address/port 
if(!socket_bind($sock, $host, $port)) 
{ 
    echo socket_last_error() ; 
    die('Could not bind to address'); 
} 
record("SOCKET BIND OK"); 

// start listening for connections 
$result = socket_listen($sock, 1024) or die("Could not set up socket listener\n"); 
record("SOCKET LISTEN OK"); 
$clients = array($sock); 


// infinite while loop 
while(1) 
{ 

    // Setup clients listen socket for reading 
    $read = $clients; 

    $e = NULL; 

    if (socket_select($read, $write = NULL, $except = NULL, 0,0) < 1) 
    { 
     continue; 
    } 

    /* if a new read ready is being made add it to the client array */ 

    if (in_array($sock, $read)) { 
     record("NEW CONNECTION"); 
     $clients[$pos] = $newsock = socket_accept($sock); 
     $curpos = $pos; 
     $pos++; 
     socket_getpeername($newsock, $ip,$port); 
     record("Incoming IP: {$ip} PORT: {$port}"); 
     // remove the listening socket from the clients-with-data array 
     $key = array_search($sock, $read); 
     unset($read[$key]); 

    } // end if in_array 

    // loop through all the clients that have data to read from 
    foreach ($read as $read_key => $read_sock) { 
     // read until newline or 1024 bytes 
     // socket_read while show errors when the client is disconnected, so silence the error messages 
     $key = $read_key; 
     $fulldata = $data = @socket_read($read_sock, 1024); 

     // check if the client is disconnected 
     if ($data === false) { 
      // remove client for $clients array 
      $key = array_search($read_sock, $clients); 
      socket_close($read_sock); 
      unset($clients[$key]); 

      record("NO DATA"); 

      // continue to the next client to read from, if any 
      continue; 
     } 


     // .. do something with $data ... 

    } 


} 

socket_close($sock);  
record("END"); 
die("DONE"); 

我试图在代码中使用socket_close()但无济于事。 CLOSE_WAIT似乎需要更长时间才能转移到下一个状态。

Answer 1

我发现在代码两个问题：

首先，第四参数（tv_sec）socket_select的应而不是0 NULL作为无用的，无限循环在Manual，0原因高CPU负载描述，而NULL将阻塞，直到发生任何事情：

tv_sec可能为零，导致socket_select（）立即返回。这对于轮询很有用。如果tv_sec为NULL（无超时），则socket_select（）可以无限期地阻塞。

第二，我认为这是CLOSE_WAIT的原因是您的测试如果$ data为false。这只适用于一个优雅的关闭连接，但正如一条评论here所说，您还可以对en空字符串进行测试。 所以改变一个行：

if (socket_select($read, $write = NULL, $except = NULL, NULL, 0) < 1) 

和对方：

// check if the client is disconnected 
if ($data === false || $data === '') { 

，你应该罚款