Handling MySql 'Too many connections' error on shared hosting - php

Question

I have a website that uses a MySql database for storing user info for signing in, and also my data. This site is hosted on a shared hosting server. The problem I'm running into is that I'm occasionally getting a SQL too many connections error. My max connections is set at the default 151.
I am using php for all my server side scripts, and using mysqli pdo connections.
Here is some sample code to show how I handle sql connections from my php scripts. I removed anything that wasn't relevant to the issue, such as input filtering, and character escaping.
<?php
require("common.php");
//get POST data
//My database query
$query = "
SELECT
id,
username,
password,
salt,
email
FROM users
WHERE
username = :username
";
//set params for prepared statements
$query_params = array(
':username' => $_POST['username']
);
try {
$stmt = $db->prepare($query);
$result = $stmt->execute($query_params);
}
catch(PDOException $ex) {
$miscErr = "Something failed, please try again.";
}
$row = $stmt->fetch();
//do my password hashing, and checking, and sign in user using data in $row
}
?>
Here is my common.php where the error is thrown. I'm not sure what the correct way is to handle it, as i would like the code to try several times before failing.
<?php
$username = "username";
$password = "**************";
$host = "localhost";
$dbname = "mydbname";
$options = array(PDO::MYSQL_ATTR_INIT_COMMAND => 'SET NAMES utf8');
$miscErr = "";
try {
$db = new PDO("mysql:host={$host};dbname={$dbname};charset=utf8", $username, $password, $options);
}
catch(PDOException $ex) {
$miscErr = "Something failed, please try again";
}
$db->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
$db->setAttribute(PDO::ATTR_DEFAULT_FETCH_MODE, PDO::FETCH_ASSOC);

Answer 1

I know this has been a while, but here is the solution that I came up with. Since there is no way for me to prevent the errors, i simply handle them with the following code in my common.php file.
$db = ""; // db object
$er = ""; // error object
/*setdb() is the function that actually gets and starts the db connection.
It returns either the db object, or false. The loop will try up to 5 times
to connect with .1 second breaks in between. if that fails then it logs an
error, and the page fails to load. This has not happened in over 5 months on
a live site.*/
for ($i = 0; $i = 5; $i++) { // short loop
if (setdb() !== false) {
$db = setdb(); // if successful breaks
break;
} else {
if ($i = 5) { // after 5 trys, logs error.
file_put_contents('sqlerror.er', $er . "\r\n", FILE_APPEND);
}
}
usleep(100000); // .1second sleep
}
function setdb(){
$username = "my-username";
$password = "***************";
$host = "localhost";
$dbname = "my_database";
$options = array(PDO::MYSQL_ATTR_INIT_COMMAND => 'SET NAMES utf8');
$miscErr = "[1040] Too many connections";
try { // try to make connection
$db = new PDO("mysql:host={$host};dbname={$dbname};charset=utf8", $username, $password, $options);
}
catch(PDOException $ex) {
$er = $ex;
$pos = strpos($ex, $miscErr);
if ($pos !== false) {
return false; //return false on error
}
file_put_contents('sqlerror.er', $ex . "\r\n", FILE_APPEND);
}
return $db; // return true
}
$db->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
$db->setAttribute(PDO::ATTR_DEFAULT_FETCH_MODE, PDO::FETCH_ASSOC);
session_start();