Memory usage issues with VPS (ubuntu): MySQL process dies - mysql

Question

I'm running a VPS, with specs:
Ubuntu 12.04.5 LTS (GNU/Linux 3.13.0-32-generic x86_64)
512mb RAM
1 CPU
20gb SSD
If you're wondering it's a DigitalOcean droplet. It's running TS3, LAMP (with wordpress), OpenVPN, BYOBU, and OwnCloud.
Now my problem is with mySQL dying on me after like 30m to 1hour. Usually after a reboot, the memory usage is 54% and mySQL doesn't have a problem, but as the memory usage goes towards 80-89% I start to get issues.
System load: 0.01 Users logged in: 0
Usage of /: 22.1% of 19.56GB IP address for eth0: *****
Memory usage: 90% IP address for as0t0: *****
Swap usage: 0% IP address for as0t1: *****
Processes: 93
As you can see, the memory usage is VERY high, and I've noticed the trend that mySQL process dies as the memory usage gets higher. However the swap usage is 0%.
Is there a way to make mySQL and the other processes to use the swap?
Would letting mySQL make use of the swap stop letting it die after my memory usage gets so high?
After the high memory usage, the process dies and I get this error:
[2002] SQLSTATE[HY000] [2002] Can't connect to local MySQL server through socket '/var/run/mysqld/mysqld.sock' (111)
The processor load never goes above 25% in most cases. The server also runs a fast SSD, so it wouldn't be a problem to use a swap, and I don't have that much traffic.

Answer 1

Fixed it, by making a swap file of size 256mb. mySQL doesn't stop now after having no available memory to work in.
After following this tutorial by Etel Sverdlov:
https://www.digitalocean.com/community/tutorials/how-to-add-swap-on-ubuntu-12-04
I was able to make a swap file. I'll copy the tutorial for the sake it gets deleted.
How To Add Swap on Ubuntu 12.04
About Linux Swapping
Linux RAM is composed of chunks of memory called pages. To free up pages of RAM, a “linux swap” can occur and a page of memory is copied from the RAM to preconfigured space on the hard disk. Linux swaps allow a system to harness more memory than was originally physically available.
However, swapping does have disadvantages. Because hard disks have a much slower memory than RAM, virtual private server performance may slow down considerably. Additionally, swap thrashing can begin to take place if the system gets swamped from too many files being swapped in and out.
Check for Swap Space
Before we proceed to set up a swap file, we need to check if any swap files have been enabled on the VPS by looking at the summary of swap usage.
sudo swapon -s
An empty list will confirm that you have no swap files enabled:
Filename Type Size Used Priority
Check the File System
After we know that we do not have a swap file enabled on the virtual server, we can check how much space we have on the server with the df command. The swap file will take 256MB— since we are only using up about 8% of the /dev/sda, we can proceed.
df
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/sda 20907056 1437188 18421292 8% /
udev 121588 4 121584 1% /dev
tmpfs 49752 208 49544 1% /run
none 5120 0 5120 0% /run/lock
none 124372 0 124372 0% /run/shm
Create and Enable the Swap File
Now it’s time to create the swap file itself using the dd command :
sudo dd if=/dev/zero of=/swapfile bs=1024 count=256k
“of=/swapfile” designates the file’s name. In this case the name is swapfile.
Subsequently we are going to prepare the swap file by creating a linux swap area:
sudo mkswap /swapfile
The results display:
Setting up swapspace version 1, size = 262140 KiB
no label, UUID=103c4545-5fc5-47f3-a8b3-dfbdb64fd7eb
Finish up by activating the swap file:
sudo swapon /swapfile
You will then be able to see the new swap file when you view the swap summary.
swapon -s
Filename Type Size Used Priority
/swapfile file 262140 0 -1
This file will last on the virtual private server until the machine reboots. You can ensure that the swap is permanent by adding it to the fstab file.
Open up the file:
sudo nano /etc/fstab
Paste in the following line:
/swapfile none swap sw 0 0
Swappiness in the file should be set to 10. Skipping this step may cause both poor performance, whereas setting it to 10 will cause swap to act as an emergency buffer, preventing out-of-memory crashes.
You can do this with the following commands:
echo 10 | sudo tee /proc/sys/vm/swappiness
echo vm.swappiness = 10 | sudo tee -a /etc/sysctl.conf
To prevent the file from being world-readable, you should set up the correct permissions on the swap file:
sudo chown root:root /swapfile
sudo chmod 0600 /swapfile
All credit to: Etel Sverdlov at: https://www.digitalocean.com/community/tutorials/how-to-add-swap-on-ubuntu-12-04