PHP socket_select（）始终检测可读取的套接字

I've been searching back and forth looking for a solution to this problem I'm having. It appears that socket_select() will always find accepted sockets (resources returned by socket_accept()) as available to read from, even though there are no packets waiting. I'm sure there's a little something I forgot to do, but I can't figure out what that is.

Here's the relevant code:

while(TRUE){
    $read_sockets=$this->client_sockets;
    $write_sockets=NULL;
    $except=NULL;

    if(socket_select($read_sockets, $write_sockets, $except, NULL)<1) continue;
    foreach($read_sockets as $pending_socket){
        echo "Read request received...".PHP_EOL;

        if($this->socket==$pending_socket){
            $new_client_socket=socket_accept($this->socket);
            socket_write($new_client_socket,$this->read_data($new_client_socket),2048);
            $this->client_sockets[]=$new_client_socket;
            echo "New client...".PHP_EOL;
        } else {
            $pending_socket_data=$this->read_data($pending_socket);
            if($pending_socket_data===false){
                unset($this->client_sockets[array_search($pending_socket,$this->client_sockets)]);
                continue;
            }
            socket_write($pending_socket,$pending_socket_data,2048);
            echo "Old client...".PHP_EOL;
        }
    }
}

private function read_data(&$socket){
    echo 'Reading data...'.PHP_EOL;
        $client_data='';$tmp='';
    while(socket_recv($socket,$tmp,$this->max_length,0) > 0){
        $client_data .= $tmp;
    }
    return $client_data;
}

I know I'm not catching some exceptions, as socket_recv === FALSE, but this code is just a proof of concept, that I had to get down to while debugging the main code.

$this->socket is the server socket, and is non-blocking.

Thank's in advance!

private function read_data(&$socket){
    echo 'Reading data...'.PHP_EOL;
        $client_data='';$tmp='';
    while(socket_recv($socket,$tmp,$this->max_length,0) > 0){
        $client_data .= $tmp;
    }
    return $client_data;
}

Method read_data never return false, so the codes below will never run.

if($pending_socket_data===false){
     unset($this->client_sockets[array_search($pending_socket,$this->client_sockets)]);
     continue;
}

When socket_recv return false ,you should check socket_last_error() and decide if to socket_close($pending_socket) and unset($this->client_sockets[..]).

When socket_recv return 0, may be socket closed and you should call unset($this->client_sockets[..]).