Hey, after update from MySQL 5.5 to 5.6, my life is getting worse. There are many 'Database connection error' when I try to open my website. And I even can not access to phpMyAdmin. What's happening.
OK, I turn on the SSH, connect to my server and BOOM, mysql is having 'Out of Memory' error, and everything crash.
That time, I need to restart mySQL:
$> sudo service mysql start
Next, I need to find out how much memory is being used, because Digital Ocean does not support this feature.
$> sudo apt-get install htop
OK, I turn on the SSH, connect to my server and BOOM, mysql is having 'Out of Memory' error, and everything crash.
That time, I need to restart mySQL:
$> sudo service mysql start
Next, I need to find out how much memory is being used, because Digital Ocean does not support this feature.
$> sudo apt-get install htop
$> htop
Now there is my memory usage:
Wow, mysqld service is consuming 48.9% memory, what!!!
There are 2 things I can do: Upgrade RAM (means upgrade Dropplet) or continue to check for another solution, my VPS is 1GB RAM.
Next, I check the log of mysql at /var/log/mysql:
There are alot of errors:
There are some problems that we can find out:
+ InnoDB can not allocate memory
+ InnoDB memory heap is disabled
Let's check the swap by this command:
$> free -m
Swap = 0 means there is no swap setup.
---> I need to setup the swap File by following steps:
https://www.digitalocean.com/community/tutorials/how-to-add-swap-on-ubuntu-14-04
There might be some errors when you try command in above pages, like:
sysctl: cannot stat /proc/sys/50: No such file or directory
What you need to do is to:
+ move to the /proc/sys/vm folder: $> cd /proc/sys/vm
Then type again
Now my system start using swap file and no out of memory error. However I always recommend you to upgrade RAM if possible because using swap file will degrade your performance.
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