database/sql: db.PingContext takes longer to time out on certain database host IPs than on others (postgresql and mysql) #27476
Description
Please answer these questions before submitting your issue. Thanks!
What version of Go are you using (go version)?
go1.10.1 linux/amd64
Does this issue reproduce with the latest release?
Yes, at least on go1.10.4 linux/amd64
What operating system and processor architecture are you using (go env)?
GOARCH="amd64"
GOHOSTARCH="amd64"
GOHOSTOS="linux"
What did you do?
Attempted to use context.WithTimeout to limit the amount of time a PingContext() command takes to try and access a database server.
package main
//Extended timeout will reproduce for both msyql and postgres
import (
"context"
"database/sql"
"log"
"time"
//_ "github.com/go-sql-driver/mysql" //MySQL driver produces same issue
_ "github.com/lib/pq" //Postgresql driver produces same issue
)
func main() {
log.Print("Trying to ping database!")
//Prepare a "context" to execute queries in, this will allow us to use timeouts
var bgCtx = context.Background()
var ctx2SecondTimeout, cancelFunc2SecondTimeout = context.WithTimeout(bgCtx, time.Second*2)
defer cancelFunc2SecondTimeout()
//Open database connection
//db, err := sql.Open("mysql", "root:@tcp(172.1.2.3)/testdb?parseTime=true")
db, err := sql.Open("postgres", "host=172.1.2.3 user=a password=b dbname=c")
if err != nil {
log.Printf("Unable to open db, %s", err.Error())
return
}
log.Print("Successfully called open()")
//Ping database connection with 2 second timeout
err = db.PingContext(ctx2SecondTimeout)
if err != nil {
log.Printf("Can't ping database server in order to use storage, %s", err.Error())
return
}
log.Print("Successfully pinged database!")
}
What did you expect to see?
A timeout of 2- seconds for 172.1.2.3
A timeout of 2- seconds for 541.1.2.3
What did you see instead?
A timeout of 2+ minutes for 172.1.2.3
(An immediate timeout for 541.1.2.3, which is ok)