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7 years ago
Improved version of using polling to check for slow query,
"KILL #ID" does not work if id of the myqsli link is the same as the one that kills it,
so you have to disconnect from mysqli and connect again with new link to 
kill the #ID.
<?php
// Slow SQL Query
      $SelectSql = 'SELECT * FROM SLOW_QUERY';
      $link = mysqli_connect('localhost','user','pass','database');
      mysqli_query($SelectSql, MYSQLI_ASYNC);
      $thread_id = mysqli_thread_id($link);
      // Ignore user abort so we can kill the query
      ignore_user_abort(true);
      $MaxTime = 5; // seconds
      $Overtime = false;
      $StartTime = time();
      do
      {
          // Poll MySQL
        $links = $errors = $reject = array($link);
        $poll = mysqli_poll($links, $errors, $reject, 0, 500000);
         // Check if the connection is aborted and the query was killed
        if (connection_aborted()) {
          $link_new = mysqli_connect('localhost','user','pass','database');
          mysqli_kill($link_new, $thread_id);
          $kill = mysqli_kill($link_new, $thread_id);
          if ($kill)
          {
            die();
          }
        }
        $EndTime = time();
        // Check overtime, kill if detected overtime
        if ($EndTime - $StartTime > $MaxTime)
        {
          $link_new = mysqli_connect('localhost','user','pass','database');
          mysqli_kill($link_new, $thread_id);
          $Overtime = true;
          echo 'Error: Query took over '.$Overtime.'.';
        }
      } while (!$poll && $Overtime == false);
?>
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