Memory seems to spike every morning

@nanne

Using top or htop will help you figure out what processes ran by what users are using the most of your resources relatively easily (you’d have to install htop – it’s the colorful version of top).

Once top is running, you can sort processes and expand them using SHIFT + M and just c. You can also hit e while top is running to change the reported memory usage to human readable format.

You can also run something like:

ps -A --sort -rss -o comm,pmem | head -n 11

To get a list of what users are using the most memory right now. Sample output would look something like this:

COMMAND         %MEM
mysqld           6.9
php-fpm7.1       2.6
php-fpm7.1       2.5
php-fpm7.1       2.5
php-fpm7.1       1.0
memcached        0.8
snapd            0.5
nginx            0.3
systemd-journal  0.2
sshd             0.1

So as you can see above, MySQL is what just so happens to be using the most memory followed by php7.1-fpm (which is actually using more, but this is broken down by process, not collectively).

@nanne not sure if you found the answer to your question but if not, this article on DO explains that the memory shown in the memory graph is Total Memory - Free - Cached:

“Memory usage is calculated by subtracting free memory and memory used for caching from the total memory amount.”

I have the same issue: I have an alarm set up for when the server uses 80% of the RAM and it gets triggered every morning at 6:25 UTC (at the same time when cron.daily crons run) but I can’t seem to be able to reproduce it by running manually the crons. It’s frustrating because I am pretty sure it’s a non-issue: there’s plenty of RAM to be used, it’s just that it’s cached.

I saw this with one of my droplets as well (strangely, only one of them) - but then someone pointed out it may be system cron jobs that are in /etc/cron.daily that run every day, causing the spike in memory.