uncaught exception FuelCoreDatabase_Exception: SQLSTATE[HY000] [2006] MySQL server gone away

Expert [addtoany]

Sep '24

The FuelCoreDatabase_Exception: SQLSTATE[HY000] [2006] MySQL server has gone away is a common error in applications connecting to MySQL. This happens when the MySQL server unexpectedly disconnects or terminates the connection while the FuelPHP application is still running.

Here are common causes and solutions for this error:

Causes:

Timeout Issues: MySQL has an wait_timeout and interactive_timeout that control how long a connection can be inactive before it is closed. If your script takes longer to execute, this timeout might be reached.
Packet Size: Sometimes the size of the query being executed is larger than the max_allowed_packet setting in MySQL.
Server Resources: Low server resources, memory issues, or high server load can result in the MySQL server closing connections.
Server Crashes: If the MySQL server crashes or restarts, the connection will be dropped.
Network Problems: If there are network connectivity issues between the FuelPHP application and the MySQL server, connections might drop.

Solution:

1. Increase `wait_timeout` and `interactive_timeout`

The wait_timeout and interactive_timeout variables control how long the MySQL server waits before closing an inactive connection. If your queries or processes take longer to execute, try increasing these values in the MySQL configuration.

Find your MySQL configuration file, typically located at /etc/my.cnf or /etc/mysql/my.cnf.
Add or update the following values:

Example


[mysqld]
wait_timeout=28800
interactive_timeout=28800

The default timeout is typically set to 8 hours (28800 seconds). You can increase this if necessary.

2. Increase `max_allowed_packet`

If the issue is related to large queries or data being sent to the MySQL server, you can increase the max_allowed_packet value.

In the MySQL configuration file:

Example


[mysqld]
max_allowed_packet=64M

You can increase this value depending on your needs (e.g., 128M or higher).

3. Restart MySQL

After making changes to the configuration, restart MySQL to apply the changes:

Example


sudo service mysql restart

4. Handle Disconnections in FuelPHP

FuelPHP may not automatically reconnect when the database connection is lost. You can set up your application to reconnect automatically.

Here’s an example of handling a lost connection in FuelPHP by adding a try-catch block to reconnect:

Example


try {
    // Attempt a query
    $result = DB::query('SELECT * FROM users')->execute();
} catch (Fuel\Core\Database_Exception $e) {
    if (strpos($e->getMessage(), 'MySQL server has gone away') !== false) {
        // Attempt to reconnect
        DB::reconnect();
        // Retry the query
        $result = DB::query('SELECT * FROM users')->execute();
    } else {
        // Throw the exception for other errors
        throw $e;
    }
}

In this code, if the "MySQL server has gone away" error occurs, the script will attempt to reconnect and retry the query.

5. Increase PHP Script Execution Time

If your script takes longer to run than the server’s timeout settings, you might want to increase the script execution time in PHP.

You can set this by adding the following line in your PHP script:

Example


set_time_limit(0); // 0 means unlimited

Or, modify the php.ini file:

Example


max_execution_time = 300; // Set to desired value in seconds

Restart your web server after modifying the php.ini file.

Code Example

Here’s a more comprehensive example handling the "MySQL server has gone away" exception in FuelPHP:

Example


function getUsers()
{
    try {
        // Run query
        return DB::query('SELECT * FROM users')->execute()->as_array();
    } catch (Fuel\Core\Database_Exception $e) {
        if (strpos($e->getMessage(), 'MySQL server has gone away') !== false) {
            // Attempt reconnection
            try {
                DB::reconnect();
                return DB::query('SELECT * FROM users')->execute()->as_array();
            } catch (Fuel\Core\Database_Exception $e) {
                // Log the error
                Log::error('Database reconnection failed: ' . $e->getMessage());
                throw $e; // Rethrow exception if reconnect fails
            }
        } else {
            // Handle other database exceptions
            Log::error('Database query failed: ' . $e->getMessage());
            throw $e;
        }
    }
}

In this example, the script tries to reconnect if the "MySQL server has gone away" error occurs and retries the query. If the reconnection fails, it logs the error.

Conclusion:

The "MySQL server has gone away" error in FuelPHP can be caused by timeouts, large queries, server crashes, or network issues. To resolve this, you should increase the wait_timeout and max_allowed_packet in MySQL, handle reconnections in your FuelPHP code, and ensure that the PHP script execution time aligns with the server’s configurations. Adding error handling mechanisms, like reconnect attempts, will help mitigate unexpected failures.

uncaught exception FuelCoreDatabase_Exception: SQLSTATE[HY000] [2006] MySQL server gone away