Pool cannot detect idle connection disconnected by MySQL and will trigger `read ECONNRESET` on newly acquired connection

MySQL will disconnect idle connections after certain time frame.

This time frame is determined by MySQL variable wait_timeout.

It seems mysql2’s pool implementation cannot detect this type of disconnection (ping is not sufficient).

And when it happens, any queries sent through the acquired connection will trigger a read ECONNRESET error.

At this moment, I have to send a SELECT 1 query to test the acquired connection before use.

And previous code that calls pool.query directly will have to be re-written.

Can Mysql2 provides two extra pool creation options:

• verifyConnectionInterval: number of seconds before pool should send SELECT 1 query to test connections in the pool.
• verifyConnection: boolean. If set true, the pool will test a connection in the pool every verifyConnectionInterval seconds.

[benbotto]

All right, @sidorares, I added a PR. The PR includes two new configuration parameters: enableKeepAlive and keepAliveInitialDelay. The former defaults to false, and the latter to 0. I opted to keep keep-alive off by default to avoid unexpected side effects in existing code.

https://github.com/sidorares/node-mysql2/pull/1081

[sidorares]

@midnightcodr published as v2.1.0