Question

I have a PHP script that shows multiple tables of data loaded via a JQuery AJAX call for a tournament scoring website. The tables are individual and team scores calculated in real-time.

Each table is checked once every minute for new scores and refreshed if needed. To do this, each table sends a quick ajax request to the last updated time for the scores… if the time is different than what the table currently has, the table is refreshed with new data.

My problem is that these tournaments can get quite large, with many participants, teams, divisions and scores and loading each table uses server resources. This is no problem if a handful of people are viewing the real-time stats, but once more than about 50 people are connected to this stats page, the server starts lagging heavily.

I would like to know what I can do to optimize the data, the ajax calls, or the server itself to run as efficiently as possible so that the server doesn’t top out so quickly. I’ve already combed through the MySQL calls and tried to optimize everything as much as possible, but it doesn’t seem to be enough.

Any ideas would be greatly appreciated!

Answer 1

You could use a cache, for example in your architecture memcache would fit very well. Every time your server receive a request your php app try to get from cache the result, if not found execute the query.

Now you can choose two different way:

• easy, wait cache expire time. When the cache is expired, server miss its search and a new query is submitted. This is usually a short term cache (seconds or minutes)
• hard, cache expire in a very far future, for example hours or even days). In this case your application refresh the cache content every time the database is updated. In this case, obviously, almost all your requests hit the cache (best performance).

This example, is based on the easy approach and the cache key is based directly on the submitted SQL.

global $memcache;
$memcache = new Memcache;

// Gets key / value pair into memcache ... called by mysql_query_cache()
function getCache($key) {
    global $memcache;
    return ($memcache) ? $memcache->get($key) : false;
}

// Puts key / value pair into memcache ... called by mysql_query_cache()
function setCache($key,$object,$timeout = 60) {
    global $memcache;
    return ($memcache) ? $memcache->set($key,$object,MEMCACHE_COMPRESSED,$timeout) : false;
}

// Caching version of mysql_query()
function mysql_query_cache($sql,$linkIdentifier = false,$timeout = 60) {
    if (($cache = getCache(md5("mysql_query" . $sql))) !== false) {
        $cache = false;
        $r = ($linkIdentifier !== false) ? mysql_query($sql,$linkIdentifier) : mysql_query($sql);
        if (is_resource($r) && (($rows = mysql_num_rows($r)) !== 0)) {
            for ($i=0;$i<$rows;$i++) {
                $fields = mysql_num_fields($r);
                $row = mysql_fetch_array($r);
                for ($j=0;$j<$fields;$j++) {
                    if ($i === 0) {
                        $columns[$j] = mysql_field_name($r,$j);
                    }
                    $cache[$i][$columns[$j]] = $row[$j];
                }
            }
            if (!setCache(md5("mysql_query" . $sql),$cache,$timeout)) {
                // If we get here, there isn't a memcache daemon running or responding
            }
        }
    }
    return $cache;
}