在Go中关闭应用程序之前是否需要关闭数据库连接？

Question

In Go, when using a SQL database, does one need to close the DB (db.Close) before closing an application? Will the DB automatically detect that the connection has died?

Answer 1

DB will do its best to detect but with no luck, it may not be able to detect. Better to release what is acquired as soon as possible.

send() system call will wait for TCP connection to send data but client won't receive anything.

1. Power failure, network issue or bare exit happened without properly releasing resources. TCP keepalive mechanism will kick in and try to detect that connection is dead.

2. Client is paused and doesn't receive any data, in this case send() will block.

As a result, it may prevent

1. Graceful shutdown of cluster.
2. Advancing event horizon if it was holding exclusive locks as a part of transaction such as auto vacuum in postgresql.

Server keepalive config could be shortened to detect it earlier. (For example, ~2h 12m default in postgresql will be very long according to workload).

There may be a hard limit on max open connections, until detection, some connections will be zombie (there, unusable but decreases limit).