ECONNREFUSED error in NodeJS + MySQL web app - mysql

Question

I have web app running on NodeJS + MySQL. Initially the web app works fine,but all of a sudden the MySQL connection gets refused with following error being thrown:
ECONNREFUSED 127.0.0.1:3306
Simply restarting the server with pm2 reload solves the issue temporarily.But again after a long span of time,the above error creeps in.
The configuration in NodeJS for making MySQL connection is as following:
"sqlconn": {
"connectionLimit": 10,
"host": "127.0.0.1",
"user": "root",
"password": "XYZ",
"database": "test",
"port": 3306,
"multipleStatements": true
}
Any idea on how to resolve this issue?
NOTE: I am using a digital ocean droplet with RAM size 512MB

Answer 1

To check what was going wrong,I opened the MySQL log file:
/var/log/mysql/error.log
The logs read something like following:
InnoDB: Initializing buffer pool, total size = 128M, instances = 1, chunk size = 128M
InnoDB: Cannot allocate memory for the buffer pool
InnoDB: Plugin initialization aborted with error Generic error
Plugin 'InnoDB' init function returned error.
Plugin 'InnoDB' registration as a STORAGE ENGINE failed.
[ERROR] Failed to initialize plugins.
So the reason was that Mysql can't restart because it's out of memory.
To resolve the memory issue,this answer can be followed : https://stackoverflow.com/a/32932601/3994271
The possible solutions as discussed in the above link are :
Increasing RAM size , or
configuring a swapfile
I decided to go with configuring a swapfile.
The following link provides details on configuring a swap file:
https://www.digitalocean.com/community/tutorials/how-to-add-swap-on-ubuntu-14-04

Answer 2

You must be not closing the mysql connections while doing the query. If you keep the connections open, it would give up after sometime.
Also there is a bug in node-mysql. You can use mysql pool.enter link description here