Golang, mysql: Error 1040: Too many connections

Question

I\'m using the github.com/go-sql-driver/mysql driver for go.

I open a database:

db, err := sql.Open(\"mysql\", str)

Then I have two fun

Answer 1

The *DB object that you get back from sql.Open doesn't corresponds to a single connection. It is better thought as a handle for the database: it manages a connection pool for you.

You can control the number of open connections with `(*DB).SetMaxOpenConns and its pair for idling connections.

So basically what happens here is that db.Query and db.QueryRow tries to acquire a connection for themselves and the DB handle doesn't put any restrictions on the number of simultaneous connections so your code panics when it opens more than what mysql can handle.