$hosts = array("host1.sample.com", "host2.sample.com", "host3.sample.com"); 
$timeout = 15; 
$status = array(); 
foreach ($hosts as $host) {  
    $errno = 0;  
    $errstr = "";  
    $s = fsockopen($host, 80, $errno, $errstr, $timeout);  
    if ($s) {  
       $status[$host] = "Connectedn";  
       fwrite($s, "HEAD / HTTP/1.0rnHost: $hostrnrn");  
      do {   
        $data = fread($s, 8192);   
        if (strlen($data) == 0) {   
        break;   
        }   
       $status[$host] .= $data;  
     }  
     while (true);  
      fclose($s);  
     }  
     else {  
       $status[$host] = "Connection failed: $errno $errstrn";  
     } 
} 
print_r($status); 
"htmlcode">

$hosts = array("host1.sample.com", "host2.sample.com", "host3.sample.com"); 
$timeout = 15; 
$status = array(); 
$sockets = array(); 
/* Initiate connections to all the hosts simultaneously */ 
foreach ($hosts as $id => $host) {  
    $s = stream_socket_client("$host:80", $errno, $errstr, $timeout,  
       STREAM_CLIENT_ASYNC_CONNECT|STREAM_CLIENT_CONNECT);  
    if ($s) {  
      $sockets[$id] = $s;  
      $status[$id] = "in progress";  
    }  
    else { $status[$id] = "failed, $errno $errstr";  
    } 
} 
/* Now, wait for the results to come back in */ 
 
while (count($sockets)) {  
   $read = $write = $sockets;  
/* This is the magic function - explained below */  
   $n = stream_select($read, $write, $e = null, $timeout);  
   if ($n > 0) {  
   /* readable sockets either have data for us, or are failed  * connection attempts */  
     foreach ($read as $r) {    
          $id = array_search($r, $sockets);    
          $data = fread($r, 8192);    
     if (strlen($data) == 0) {   
          if ($status[$id] == "in progress") {   
            $status[$id] = "failed to connect";   
          }   
     fclose($r);   
     unset($sockets[$id]);    
      }  
      else {   
         $status[$id] .= $data;    
      }  
    }  
/* writeable sockets can accept an HTTP request */  
foreach ($write as $w) {   
     $id = array_search($w, $sockets);   
     fwrite($w, "HEAD / HTTP/1.0rnHost: "   
     . $hosts[$id] . "rnrn");   
     $status[$id] = "waiting for response";  
     }  
}  
else {  
/* timed out waiting; assume that all hosts associated  * with $sockets are faulty */  
foreach ($sockets as $id => $s) {   
     $status[$id] = "timed out "  
     . $status[$id];  
     }  
break;  
 } 
} 
foreach ($hosts as $id => $host) {  
   echo "Host: $hostn"; echo "Status: "  
   . $status[$id] . "nn"; 
}  
"htmlcode">

// This value is correct for Linux, other systems have other values 
define('EINPROGRESS', 115); 
function non_blocking_connect($host, $port, &$errno, &$errstr, $timeout) {  
    $ip = gethostbyname($host);  
    $s = socket_create(AF_INET, SOCK_STREAM, 0);  
    if (socket_set_nonblock($s)) {  
      $r = @socket_connect($s, $ip, $port);  
      if ($r || socket_last_error() == EINPROGRESS) {   
         $errno = EINPROGRESS;   
         return $s;  
        }  
     }  
    $errno = socket_last_error($s);  
    $errstr = socket_strerror($errno);  
    socket_close($s);  
    return false; 
} 
?> 



现在用socket_select()替换掉stream_select()，用socket_read()替换掉fread()，用socket_write()替换掉fwrite()，用socket_close()替换掉fclose()就可以执行脚本了！

PHP5的先进之处在于，你可以用stream_select()处理几乎所有的stream。例如你可以通过include STDIN用它接收键盘输入并保存进数组，你还可以接收通过proc_open()打开的管道中的数据。
希望通过这篇文章，大家可以巧妙解决PHP无法实现多线程的问题。