Managing Long-Running MySQL Queries to Prevent `max_user_connections` Issues
When facing issues related to `max_user_connections` in MySQL, managing long-running queries effectively can help alleviate the problem. Follow these steps to create a solution that automatically terminates queries that have been running for an extended period.
#### Step 1: Create a PHP Script
1. **Create the PHP File:**
Create a file named `kill_long_queries.php` in your server's directory.
2. **Write the Script:**
Copy and paste the following code into `kill_long_queries.php`:
<?php
// Replace with your MySQL credentials
$mysqli = new mysqli("localhost", "username", "password", "dbname");
// Check the connection
if ($mysqli->connect_errno) {
echo "Failed to connect to MySQL: " . $mysqli->connect_error;
exit();
}
// Get the list of running processes
$result = $mysqli->query("SHOW FULL PROCESSLIST");
// Check for query errors
if (!$result) {
echo "Error: " . $mysqli->error;
exit();
}
// Loop through the results and terminate long-running queries
try {
while ($row = $result->fetch_assoc()) {
// Check if the query has been running for more than 10 minutes (600 seconds)
if ($row['Time'] > 600) {
// Terminate the long-running query
$mysqli->query("KILL " . $row['Id']);
}
}
} catch (Exception $e) {
echo "Error: " . $e->getMessage();
}
// Close the connection
$mysqli->close();
?>
- **Note:** Replace `username`, `password`, and `dbname` with your MySQL credentials.
#### Step 2: Set Up a Cron Job
1. **Configure the Cron Job:**
Set up a cron job on your server to run the `kill_long_queries.php` script periodically. This ensures that long-running queries are automatically terminated.
2. **Cron Job Command:**
Use the following command to configure the cron job:
```bash
/usr/local/bin/php /home/webaddress/public_html/kill_long_queries.php
```
- **Note:** Replace `/home/webaddress/public_html/kill_long_queries.php` with the path to your PHP script.
3. **Set Cron Job Frequency:**
Configure the cron job to run at your desired frequency (e.g., every 5 minutes). You can do this by editing your `crontab` file:
crontab -e
Add the following line to schedule the job:
*/5 * * * * /usr/local/bin/php /home/webaddress/public_html/kill_long_queries.php
- This example runs the script every 5 minutes. Adjust the schedule as needed.
