用Kohana 3处理“警告：mysql_connect（）：连接过多”的最佳方法是什么？

Question

I've got a web application that is used by a company for logging their employees' work.

A lot of people are often logged in at once.

The application runs on a shared host.

I sometimes receive...

Warning: mysql_connect() [function.mysql-connect]: Too many connections

Which then lets further errors cascade... like errors with mysql_select_db() , mysql_error() , mysql_errnon() and finally the uncaught Database_Eexception .

When I run my main request, I wrap it in a try and capture any exception and display a not found page. This is because usually my controllers throw exceptions if a resource is not found (though the route may be valid) eg http://example.com/products/30 is a valid route, but product #30 doesn't exist.

What is the best way to handle the too many connections ? Ideally I'd like to capture that exception separately, then display a nice page that informs the employee to try again in 5 minutes.

The code that runs my main request in application/bootstrap.php looks like this...

$request = Request::instance();

try {
    $request->execute();
} catch (Exception $e) {

    if (Kohana::$environment === Kohana::DEVELOPMENT) throw $e;

    // Log the error
    Kohana::$log->add(Kohana::ERROR, Kohana::exception_text($e));

    // Create a 404 response
    $request->status = 404;
    $request->response = Request::factory(Route::get('catch_all')->uri(array('path' => 'errors/404')))->execute();
}

$request->send_headers();
echo $request->response;

Thanks for any help!

Answer 1

You might want to begin by checking to see what your MySQL system property max_connections is currently set to, and see how that compares usage requirements. If you don't have a good handle on usage requirements then you could do worse than instrument your code to log data about simultaneous connections; or your a live database profiling tool to monitor this.

You could also look to see if your code is hogging connections for too long (ie. unnecessarily) and correct this. Perhaps investigate connection pooling.

Answer 2

I just created such file to handle all the errors:

<?php

class Kohana extends Kohana_Core
{
  /**
   * Redirect to custom exception_handler
   */
  public static function exception_handler(Exception $e)
  {
    if (Kohana::DEVELOPMENT === Kohana::$environment)
    {
      // Pass to Kohana if we're in the development environment
      parent::exception_handler($e);
    }
    else
    {
      Kohana::$log->add(Kohana::ERROR, Kohana::exception_text($e));

      // Default route
      $route = Route::url('default', array('controller' => 'error', 'action' => '404'));

      // Error sub-request.
      echo Request::factory($route)
        ->execute()
        ->send_headers()
        ->response;
    }
  }
}

For now it is just a sketch, but it could give you some ideas.

ps: my bootstrap is not modified

Answer 3

In /etc/my.cnf under the [mysqld] section add:

max_connections = 500

Then either execute SET GLOBAL max_connections = 500; in MySQL or restart MySQL.