Question

My droplet keeps going down. Trying to optimize MySQL

I keep getting errors like “Out of memory: Kill process 837 (mysqld) score 68 or sacrifice child” and my server goes down atleast 4-5 a week

So I am trying to address two possible causes before giving up and just upgrading the droplet.

First, is my swap size too low? Here’s my output for free -m

Second, I installed and used mysqltuner. What parameter should I optimize in mysql? Here’s my output for mysqltuner

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Hello, @SamN

You will most definitely need to upgrade your droplet as you’re running out of memory and your application/website needs more resources in order to continue to operate.

What you can also do is to use the MySQLTuner script.

The MySQLTuner is a script written in Perl and allows you to quickly test your MySQL configuration and it gives you suggestions for adjustments to increase performance and stability.

According to the official GitHub page, it supports 300 indicators for MySQL/MariaDB/Percona Server in this last version.

To run the script you could do the following:

  • SSH to your Droplet
  • Download the script:
wget http://mysqltuner.pl/ -O mysqltuner.pl
  • Then execute it:
perl mysqltuner.pl

The script would run multiple checks against your MySQL instance, all checks done by MySQLTuner are documented here.

Also as stated in the official documentation, it is still extremely important for you to fully understand each change you make to a MySQL database server. If you don’t understand portions of the script’s output, or if you don’t understand the recommendations, you should consult a knowledgeable DBA or system administrator that you trust.

As a good practice make sure to always test your changes on staging environments before implementing them on your production database.

On the same note, if you want to have a worry-free MySQL hosting and focus on your application, I would recommend trying out the DigitalOcean Managed Databases:

https://www.digitalocean.com/products/managed-databases-mysql/

This was mini tutorial was posted from @bobbyiliev in this question in our community: https://www.digitalocean.com/community/questions/how-to-tweak-mysql-mariadb-configuration-for-increased-performance-and-stability

Hope that this helps! Regards, Alex

This issue boils down to the shared resources on the host. If wordpress uses sub-optimal queries then MySQL is forced to create temporary objects in memory and more connections to wordpress compounds the issue. If you add more SWAP space things may survive longer but will be inevitably slow.

I’d recommend

Good luck