Score:1

Server

Memory consumption on virtual server too large for applications being run

Mike Hermary

7/26/24, 7:10 PM

I have a Linux Ubuntu virtual server at Digital Ocean with the following specs: 1 vCPU, 2GB of memory, and 25GB of SSD storage.

The server is running a single WordPress website with around 400 unique visitors per day. A caching plugin has been installed and configured. Redis is also installed and configured on the server.

I have setup a memory usage notice in the control panel of Digital Ocean and I am being notified multiples times a day that the server has crossed the 70% threshold for usage.

When I run htop in the terminal, MEM is being shown as using 1.2GB to 1.4GB of 1.92GB at any given moment. SWAP is shown to be using 39.2MB of 2.00GB.

When I view the peak memory usage in the Query Monitor plugin installed in WordPress, it shows only 3.2% of 768 MB server limit being used. I have defined the PHP memory limit to be 768MB in the WordPress configuration file. These numbers seem to run in contrast to what the server is telling me related to memory usage on the server.

In my server's my.cnf, I have the following parameters set:

performance_schema = off
innodb_buffer_pool_size = 512M
key_buffer_size = 64M
max_connections = 400

Can anyone suggest where the memory hogging me be taking place on the server?

1 + 15

mysql

linux

php

memory

wordpress

HBruijn

7/26/24, 8:01 PM

Why should 30% of your memory remain unused? Your memory is there to be used. https://www.linuxatemyram.com/

Romeo Ninov

7/26/24, 8:07 PM

Questions on Server Fault must be about managing information technology systems in a business environment. Home and end-user computing questions may be asked on Super User, and questions about development, testing and development tools may be asked on Stack Overflow.

symcbean

7/26/24, 8:39 PM

Your config and metrics are all over the place. What "server limit"? What have you done to analyze the usage? How exactly did you php's memory limit?

Rick James

7/27/24, 1:00 AM

What version of MySQL?

Mike Hermary

7/27/24, 3:26 PM

@RickJames The server is running MySQL 8.0.33

Mike Hermary

7/27/24, 3:28 PM

@symcbean The memory limit was set in the PHP 8.0 FPM configuration file. I have tested from a low of 128MB up to 768MB. The same issues occur at all levels.

Rick James

7/27/24, 4:00 PM

@MikeHermary - OK, that is an upper limit. If the PHP code does get out of control, it would be better to crash PHP because of hitting the limit than crash the system due to running out of swap space.

Mike Hermary

7/27/24, 4:50 PM

@RickJames I have changed the memory limit in the php.ini file to 256M. In the WordPress configuration file, I have set the memory limit to 128M with the max memory limit set to 256M. There have been no PHP crashes yet.

Mike Hermary

7/29/24, 5:05 PM

@RickJames The server is still encountering memory utilization issues throughout the day. Do you have any other suggestions?

Rick James

7/29/24, 5:29 PM

What is on the 2GB machine? OS+WP+PHP+Apache+MySQL; anything else? You may need to upgrade to 4GB.

Mike Hermary

7/29/24, 5:41 PM

@RickJames The server stack is as follows: Ubuntu 22 LTS, WP, PHP FPM, Nginx, and MySQL 8

Rick James

8/2/24, 4:06 PM

And what plugins for WP? A "caching plugin" sounds like a memory hog; get rid of it.

Rick James

8/2/24, 4:07 PM

PHP's memory limit applies only to PHP.

Mike Hermary

8/2/24, 8:21 PM

@RickJames Should all caching be managed by Nginx, PHP, and Redis directly on the server?

Rick James

8/2/24, 8:36 PM

Each product, plus MySQL, has its own caching configuration and management. However, increasing the setting for one product will leave less RAM for the others, but without notifying them.

Score:2

Server

Rick James

7/27/24, 12:59 AM

SHOW STATUS LIKE 'Max_used_connections'; -- It will probably say much less than the 400 allocated; lower max_connections to, say, 30.
You should not be using MyISAM; lower `key_buffer_size to 20M
Remove the caching; you probably don't have enough activity to warrant the extra cache layers. Anyway, the buffer_pool does most of the work. This, on the other hand, improves the indexes to improve performance. It takes very little RAM: WP Index Improvements
"PHP memory limit to be 768MB" -- That seems extremely high. Also it is per connection. Lower it to, say, 100MB. If PHP crashes, then let's look at simplifying the webpage that caused the crash.
If you still have memory troubles, lower innodb_buffer_pool_size.

+ 8

Wilson Hauck

7/27/24, 1:57 PM

@Mike-Hermary If you still need assistance, please let us know.

Mike Hermary

7/27/24, 3:58 PM

@RickJames The WordPress tables are mostly using the InnoDB schema. A couple of tables are using MyISAM. I have implemented the other suggestions. Now when I navigate to some pages, a database connection error is displayed intermittently.

Rick James

7/27/24, 4:01 PM

A couple of _your_ tables are MyISAM? Consider converting them.

Mike Hermary

7/27/24, 4:55 PM

@RickJames Can I convert them safely with MySQL in the terminal via SSH?

Rick James

7/27/24, 6:40 PM

`ALTER TABLE tbl ENGINE=InnoDB`. More discussion of possible (rare) hiccups: http://mysql.rjweb.org/doc.php/myisam2innodb

Mike Hermary

7/28/24, 5:28 PM

@RickJames Thanks! I used a plugin to successfully change the engine for the few tables in WordPress.

Rick James

7/28/24, 6:33 PM

@MikeHermary What was the name of the plugin?

Mike Hermary

7/28/24, 6:37 PM

@RickJames I use WP Optimize to handle caching and database optimizations on my WordPress websites. It allows for engine alterations.

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