Closed
Description
When running the GET_LOCK() SQL statement with a too long lock name via db.Exec on a MySQL 5.7 the statement seems to hang.
The maximum name of the name of the lock given to GET_LOCK() in MySQL 5.7 is shorter than the one in MySQL 5.6. So I would expect an error to be returned, but this doesn't happen.
It looks like it gets a ErrBadConn and then retries a few times as described on https://www.vividcortex.com/blog/2015/01/19/gos-connection-pool-retries-and-timeouts/
So it probably takes 10*timeout before it really returns.
This is the behaviour of a mysql session:
mysql-5.7> SELECT GET_LOCK('aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa', '5');
ERROR 3057 (42000): Incorrect user-level lock name 'aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa'.
Testcase:
package main
import (
"database/sql"
_ "github.com/go-sql-driver/mysql"
)
func main () {
db, err := sql.Open("mysql", "user:host@tcp(127.0.0.1:3306)/mydb")
if err != nil { panic(err.Error()) }
res, err := db.Exec("SELECT VERSION()")
if err != nil { panic(err.Error()) } else { println(res) }
res, err = db.Exec("SELECT VERSION()")
if err != nil { panic(err.Error()) } else { println(res) }
res, err = db.Exec("SELECT GET_LOCK('aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa', '5')")
if err != nil { panic(err.Error()) } else { println(res) }
res, err = db.Exec("SELECT VERSION()")
if err != nil { panic(err.Error()) } else { println(res) }
res, err = db.Exec("SELECT VERSION()")
if err != nil { panic(err.Error()) } else { println(res) }
}
Current behavior: The testcase will run the first two SELECT VERSION() statements and print res and than hangs.
Expected behavior: Quickly return an error