Question

Could you please help me to customize the following cron script in PHP. The script is creating many background process in the server. After a day the server is going busy and MYSQL server is crashed.

What is wrong with the following script. I need this script to listen to a particular UDP port continually. So it is set as a cron jon which will run every mits.

set_time_limit(60);
class pingtype
{
function rotate()
{

    $socket = socket_create(AF_INET, SOCK_DGRAM, SOL_UDP);
    socket_bind($socket, '50.50.50.50', 9091);
    $from = '';
    $port = 0;
    $bytes_received = socket_recvfrom($socket, $buf, 150, MSG_PEEK, $from, $port);
    if ($bytes_received == -1)
    {
            die('An error occured while receiving from the socket');
            echo "Received $buf from $from\n";
    }

    echo "Received $buf from remote address $from and remote port $port";

    $hex_string_buf = "HEX: ".$this->strToHex($buf)."  String: ".$buf;

    $link = mysql_connect("localhost", "user_database", "123") or die ("Errror in connection ".mysql_error());
    mysql_select_db("database") or die ("Error in select ".mysql_error());

    $sql = "INSERT INTO socket SET contents='".$hex_string_buf."' ";
    mysql_query($sql) or die ("Error in query ".mysql_error());
    mysql_close($link);
    // close socket and delete own .sock file
    socket_close($socket);      
    usleep(1000);       
}
function strToHex($string)
{
    $hex='';
    for ($i=0; $i < strlen($string); $i++)
    {
        $hex .= str_pad(dechex(ord($string[$i])), 3);
    }
    return $hex;
}

function hexToStr($hex)
{
    $string='';
    for ($i=0; $i < strlen($hex)-1; $i+=2)
    {
        $string .= chr(hexdec($hex[$i].$hex[$i+1]));
    }
    return $string;
}
}



for($i=1;$i<=6000;$i++)
{
    $object_pingtype = new pingtype();  
    $object_pingtype->rotate();
}

Answer 1

You are overloading your server. If the script runs every minute, then this code is executed:

for($i=1;$i<=6000;$i++)
{
    $object_pingtype = new pingtype();  
    $object_pingtype->rotate();
}

This boils down to 6000 / 60 ~ 100 requests per second. If the server has not enough capacaty it will not finish this script in 60 seconds. And then a new script is started etc. etc.

In the end of the day, your server will breakdown of al the tasks.

Either:

• Decrease the number of rotate’s in the loop
• Decrease the times a script run’s per hour.