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Laravel Database Connections Not Closing with Apache2 on AWS ALB (EC2 Target Group)

Updated: Feb 14, 2025

Laravel Database Connections Not Closing with Apache2 on AWS ALB (EC2 Target Group)

When using Laravel with Apache2 on AWS ALB (Elastic Load Balancer) and EC2 Target Group, you might encounter an issue where database connections are not closing properly. This can lead to increased database usage and potential performance issues. In this answer, we will discuss the possible causes and solutions for this problem.

Causes:

  1. Apache2 Processes not terminating: When Apache2 processes are not terminating properly, they can keep the database connections open even after the request has been processed. This can be caused by various reasons such as misconfigured Apache2 settings, long-running scripts, or memory leaks.
  2. Laravel's Connection Pooling: Laravel uses connection pooling to manage database connections. This means that Laravel keeps a certain number of connections open in a pool, and reuses them for subsequent requests. However, if the connections are not being released properly, it can lead to an increase in the number of open connections, which can cause performance issues and potential database overload.
  3. AWS ALB and EC2 Target Group: When using AWS ALB and EC2 Target Group, the load balancer distributes incoming requests to multiple EC2 instances. If the database connections are not being released properly on one instance, it can affect the performance of other instances in the target group.

Solutions:

  1. Restart Apache2: The simplest solution is to restart Apache2 to terminate all running processes and release the database connections. You can do this by running the following command:
sudo systemctl restart apache2
  1. Configure Apache2 to terminate processes properly: You can configure Apache2 to terminate processes properly by setting the MaxRequestsPerChild directive in the Apache2 configuration file (httpd.conf). This directive specifies the maximum number of requests a child process should serve before terminating. By default, it is set to 0, which means that the child process never terminates. You can set it to a reasonable value, such as 1000, to ensure that the child process terminates after serving a certain number of requests.
sudo nano /etc/apache2/mods-available/mpm-prefork.conf

Find the following line:

ServerTokens Prod
ServerSignature Off

Add the following line below it:

<IfModule mpm_prefork_module>
    StartServers 2
    ServerLimit 5
    MaxClients 15
    MaxRequestsPerChild 1000
</IfModule>

Save and exit the file. Restart Apache2 to apply the changes:

sudo systemctl restart apache2
  1. Configure Laravel to release database connections: Laravel provides a way to release database connections manually by calling the DB::disconnect() method. You can add this method to the terminate method of the App\Http\Middleware\TrimStrings middleware, which is automatically registered by Laravel. This middleware is executed at the end of every request, making it an ideal place to release the database connections.
namespace App\Http\Middleware;

use Closure;
use Illuminate\Support\Facades\DB;

class TrimStrings
{
    /**
     * Handle an incoming request.
     *
     * @param  \Illuminate\Http\Request  $request
     * @param  \Closure  $next
     * @return mixed
     */
    public function handle($request, Closure $next)
    {
        // Release database connections
        DB::disconnect();

        // Continue processing the request
        return $next($request);
    }

    /**
     * Terminate the request after it has been processed.
     *
     * @param  \Illuminate\Http\Request  $request
     * @param  \Symfony\Component\HttpFoundation\Response  $response
     * @return void
     */
    public function terminate($request, $response)
    {
        // Release database connections
        DB::disconnect();
    }
}

  1. Monitor database usage: To prevent potential database overload, it is important to monitor database usage regularly. You can use various tools, such as AWS RDS Dashboard, MySQL Workbench, or Laravel's built-in database performance monitoring, to monitor the number of open connections, query performance, and other metrics.

  2. Use Laravel's built-in connection pooling: Laravel's built-in connection pooling can help manage database connections efficiently and prevent performance issues. You can configure the number of connections in the .env file:

DB_CONNECTION=mysql
DB_HOST=127.0.0.1
DB_PORT=3306
DB_DATABASE=mydatabase
DB_USERNAME=myusername
DB_PASSWORD=mypassword
DB_POOL=true
DB_QUEUES=sql,redis
DB_FOUNDATION_CONNECTIONS=30

The DB_FOUNDATION_CONNECTIONS option specifies the number of connections in the pool. You can adjust this value based on your requirements.

Conclusion:

In conclusion, when using Laravel with Apache2 on AWS ALB and EC2 Target Group, database connections not closing properly can lead to performance issues and potential database overload. The possible causes include Apache2 processes not terminating, Laravel's connection pooling, and AWS ALB and EC2 Target Group. The solutions include restarting Apache2, configuring Apache2 to terminate processes properly, configuring Laravel to release database connections, monitoring database usage, and using Laravel's built-in connection pooling. By implementing these solutions, you can ensure that your Laravel application runs efficiently and effectively on AWS ALB and EC2 Target Group.

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