Question

Out Of Memory? Or Memory Leak

Posted March 22, 2015 4.9k views
UbuntuMySQLPHPDigitalOceanLEMP

I seem to have server crashes every 24-48 hours, the server memory keeps climbing up until the server runs out of memory then kills off the children.

I can fix the problem by restarting php5-fpm but I don’t want to keep doing that.

It is just using a LEMP stack with Wordpress Buddypress but I suspect there may be a memory leak?

I am already using a 4gb Swap file on a $10 vps. Any ideas?

Thanks

1 comment
  • Solution short term:

    service mysqld restart (redhat)
    service mysql restart (debian/ubuntu) to restart the mysql server

    sudo /etc/init.d/mysql stop
    sudo /etc/init.d/mysql start

    reboot

    This indeed only gives short solution, it seems mySQL is doing something eating memory. It is performance_schema=FALSE missing in your mySQL files!!


    What to do:

    open your terminal…

    pwd (what dir am i in?)
    ll or la (list files)
    cd / (go to root)
    cd /etc/mysql/mysql.conf.d/
    nano mysqld.cnf (open in editor, or one of the other mysql files)

    scroll to the bottom and add (it will turn off this feature in mySQL)
    add performance_schema=FALSE

    some other options i found can also be added (not tested)

    [mysqld]
    performanceschema
    performance
    schemaeventswaitshistorysize=20
    performanceschemaeventswaitshistorylongsize=15000

    and service mysql restart and the command reboot. Check your control panel and monitor if the server stays stable in memory & cpu use.

    No enjoy some sunshine (after days of debugging :D)

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2 answers

Without logs and more details is hard to say the cause, 4gb SWAP is terrible big and won’t resolve your problem.

Try adding some caching to your droplet/site with Cloudflare - Varnish, and Total Cache plugin, also use APC for mysql caching. Be sure that PHP-FPM is optimized, maybe you have too much memory and processes assigned to it, which doesn’t mean it will be able to handle more traffic.

Hello, all

What you can also do is to use the MySQLTuner script. in order to make sure that your MySQL config is using the recommended values against the available resources on your server.

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