使用持久连接时连接过多

Question

I have a small blog with more than 400 online visitors per minutes.

Since there is many connection request needed I'm using a persistent connection to reuse it when it's possible, here is my connection class:

<?php
    class DatabaseConnection {

        var $currCon;

        public function connect() {
            require_once '/config.php';

            try {

                $this->currCon = new PDO('mysql:host=' . DB_HOST . ';dbname=' . DB_DATABASE, DB_USER, DB_PASSWORD, array(
                    PDO::MYSQL_ATTR_INIT_COMMAND => "SET NAMES utf8", 
                    PDO::ATTR_PERSISTENT => true
                ));

            } catch (Exception $e) {
                header('HTTP/1.1 503 Service Temporarily Unavailable');
                header('Status: 503 Service Temporarily Unavailable');
                header('Retry-After: 300');
                die("Can't connect to MySQL database<br />: " . $e);
            }
        }

        public function disconnect() {
            // Unused for PERSISTENT connections
            // $this->currCon = null;
            // unset($this->currCon);
        }

        public function getDatabaseConnection() {
            return $this->currCon;
        }
    }
?>

The problem is that I got many errors which said Too many connection and That's interesting because I'm using persistent connection model!

Also I changed my MySQL service config and increasing max_connection value from 150 to 500 but the problem still persist!

Any ideas to how avoid from this error!?

Answer 1

1. make it

    PDO::ATTR_PERSISTENT => FALSE 

   most likely this will be enough.

2. Also make sure you are calling DatabaseConnection::connect() only ONCE

Answer 2

In such type of application the better approach would be not to use a persistent connection at all. If the MySQL server is on the same machine, the benefit of the persistent connection is minor.

This has been already discussed here https://stackoverflow.com/a/5323928/1800369