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Question

Wordpress - mysql crash

Hello what’s wrong on Digital Ocean?

I have a droplet with 1 GB Memory / 30 GB Disk / AMS2 - Ubuntu 16.04.2 x64 and it work very well in the last 2 months.

Now i want know why in the last 4 days mysql stop working??? i really don’t understand why this occured, i have one more droplet with same specs and more Wordpress site on it, and work very well.

problem is related to ram consuption, but i try a2dissite all my sites and leave just one active, problem persist!!!

tail -40 /var/log/mysql/error.log

2017-07-24T19:04:30.218958Z 0 [Note] InnoDB: Number of pools: 1 2017-07-24T19:04:30.219177Z 0 [Note] InnoDB: Using CPU crc32 instructions 2017-07-24T19:04:30.222532Z 0 [Note] InnoDB: Initializing buffer pool, total siz e = 128M, instances = 1, chunk size = 128M 2017-07-24T19:04:30.222644Z 0 [ERROR] InnoDB: mmap(137428992 bytes) failed; errn o 12 2017-07-24T19:04:30.222824Z 0 [ERROR] InnoDB: Cannot allocate memory for the buf fer pool 2017-07-24T19:04:30.222864Z 0 [ERROR] InnoDB: Plugin initialization aborted with error Generic error 2017-07-24T19:04:30.222887Z 0 [ERROR] Plugin ‘InnoDB’ init function returned err or. 2017-07-24T19:04:30.222904Z 0 [ERROR] Plugin ‘InnoDB’ registration as a STORAGE ENGINE failed. 2017-07-24T19:04:30.222921Z 0 [ERROR] Failed to initialize plugins. 2017-07-24T19:04:30.222935Z 0 [ERROR] Aborting

2017-07-24T19:04:30.222951Z 0 [Note] Binlog end 2017-07-24T19:04:30.223066Z 0 [Note] Shutting down plugin ‘MyISAM’ 2017-07-24T19:04:30.223766Z 0 [Note] /usr/sbin/mysqld: Shutdown complete

2017-07-24T19:05:00.448335Z 0 [Warning] Changed limits: max_open_files: 1024 (re quested 5000) 2017-07-24T19:05:00.448433Z 0 [Warning] Changed limits: table_open_cache: 431 (r equested 2000) 2017-07-24T19:05:00.658943Z 0 [Warning] TIMESTAMP with implicit DEFAULT value is deprecated. Please use --explicit_defaults_for_timestamp server option (see doc umentation for more details). 2017-07-24T19:05:00.662549Z 0 [Note] /usr/sbin/mysqld (mysqld 5.7.19-0ubuntu0.16 .04.1) starting as process 5831 … 2017-07-24T19:05:00.672747Z 0 [Note] InnoDB: PUNCH HOLE support available 2017-07-24T19:05:00.672879Z 0 [Note] InnoDB: Mutexes and rw_locks use GCC atomic builtins 2017-07-24T19:05:00.672910Z 0 [Note] InnoDB: Uses event mutexes 2017-07-24T19:05:00.673003Z 0 [Note] InnoDB: GCC builtin __atomic_thread_fence() is used for memory barrier 2017-07-24T19:05:00.673107Z 0 [Note] InnoDB: Compressed tables use zlib 1.2.8 2017-07-24T19:05:00.673136Z 0 [Note] InnoDB: Using Linux native AIO 2017-07-24T19:05:00.674193Z 0 [Note] InnoDB: Number of pools: 1 2017-07-24T19:05:00.674524Z 0 [Note] InnoDB: Using CPU crc32 instructions 2017-07-24T19:05:00.677755Z 0 [Note] InnoDB: Initializing buffer pool, total siz e = 128M, instances = 1, chunk size = 128M 2017-07-24T19:05:00.677867Z 0 [ERROR] InnoDB: mmap(137428992 bytes) failed; errn o 12 2017-07-24T19:05:00.677951Z 0 [ERROR] InnoDB: Cannot allocate memory for the buf fer pool 2017-07-24T19:05:00.677980Z 0 [ERROR] InnoDB: Plugin initialization aborted with error Generic error 2017-07-24T19:05:00.677996Z 0 [ERROR] Plugin ‘InnoDB’ init function returned err or. 2017-07-24T19:05:00.678006Z 0 [ERROR] Plugin ‘InnoDB’ registration as a STORAGE ENGINE failed. 2017-07-24T19:05:00.678017Z 0 [ERROR] Failed to initialize plugins. 2017-07-24T19:05:00.678025Z 0 [ERROR] Aborting

2017-07-24T19:05:00.678051Z 0 [Note] Binlog end 2017-07-24T19:05:00.678201Z 0 [Note] Shutting down plugin ‘MyISAM’ 2017-07-24T19:05:00.679034Z 0 [Note] /usr/sbin/mysqld: Shutdown complete

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alexdo • October 23, 2020

Hello, all

The key error here is:

InnoDB: Fatal error: cannot allocate memory for the buffer pool

This crash is due to your system running out of memory. I’d suggest that you add a swap file to give yourself a bit more of a buffer. Check out this tutorial:

How To Add Swap on Ubuntu 14.04

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

alexdo • October 19, 2020

Hello, all

You can also create a simple bash script to check if MySQL is running and if not to restart it.

#!/bin/bash

# Check if MySQL is running
sudo service mysql status > /dev/null 2>&1

# Restart the MySQL service if it's not running.
if [ $? != 0 ]; then
    sudo service mysql restart
fi

Run this script every 5 minutes using a cron job like this one:

 */5 * * * * /home/user/scripts/monitor.sh > /dev/null 2>&1

Hope that this helps! Regards, Alex

DigitalCarrot • July 24, 2017

I had memory issues with my droplet hosting just a couple of WordPress sites with very low traffic.

However, I added the following to my apache2.conf:

<files xmlrpc.php>
        order allow,deny
        deny from all
</files>

My issues with MariaDB running out of RAM seem to have disappeared after doing this, so I suspect it could have been an XML RPC attack against WordPress.

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