- Check Current Memory Usage: Run `SHOW ENGINE INNODB STATUS;` to check the InnoDB memory allocation.
- Identify Large Queries: Execute `SHOW FULL PROCESSLIST;` to identify any long-running or large queries that might be consuming excessive memory.
- Optimize Problematic Queries: Use the information from the previous step to optimize or kill any problematic queries. To kill a query, use `KILL [query ID];`
- Clear Query Cache: If query cache is enabled, clear it by executing `FLUSH QUERY CACHE;`
- Check Table Locks: Run `SHOW OPEN TABLES WHERE In_use > 0;` to identify if there are any tables locked, consuming memory.
- Reduce Memory Usage: Temporarily reduce the `innodbbufferpoolsize` (if it's set very high) to free up some memory. Use `SET GLOBAL innodbbufferpoolsize = [desired size];` Make sure to adjust this to a safe value that won't impact your system's performance negatively.
- Restart MySQL Service: If possible and as a last resort, restart the MySQL service to clear the memory. Use your system's service management commands for this, such as `sudo systemctl restart mysql` on Linux.
8. Check Error Log: Finally, check the MySQL error log for any additional clues. The location of the log file varies but can often be found in `/var/log/mysql/error.log` or by running `SHOW VARIABLES LIKE 'log_error';`