database/sql: SetConnMaxIdleTime, SetConnMaxLifetime order impacts close time

[eqinox76]

What version of Go are you using (go version)?

$ go version
go version go1.16.3 linux/amd64

Does this issue reproduce with the latest release?

Yes

What operating system and processor architecture are you using (go env)?

go env Output

$ go env
GO111MODULE=""
GOARCH="amd64"
GOBIN=""
GOCACHE="/home/carsten/.cache/go-build"
GOENV="/home/carsten/.config/go/env"
GOEXE=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOINSECURE=""
GOMODCACHE="/home/carsten/go/pkg/mod"
GONOPROXY="dev.azure.com/xtp"
GONOSUMDB="dev.azure.com/xtp"
GOOS="linux"
GOPATH="/home/carsten/go"
GOPROXY="https://proxy.golang.org,direct"
GOROOT="/snap/go/7360"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/snap/go/7360/pkg/tool/linux_amd64"
GOVCS=""
GOVERSION="go1.16.3"
GCCGO="gccgo"
AR="ar"
CC="gcc"
CXX="g++"
CGO_ENABLED="1"
GOMOD="/dev/null"
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -m64 -pthread -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build3305456222=/tmp/go-build -gno-record-gcc-switches"
GOROOT/bin/go version: go version go1.16.3 linux/amd64
GOROOT/bin/go tool compile -V: compile version go1.16.3
uname -sr: Linux 5.8.0-50-generic
Distributor ID:	Ubuntu
Description:	Ubuntu 20.04.2 LTS
Release:	20.04
Codename:	focal
/lib/x86_64-linux-gnu/libc.so.6: GNU C Library (Ubuntu GLIBC 2.31-0ubuntu9.2) stable release version 2.31.
gdb --version: GNU gdb (Ubuntu 9.2-0ubuntu1~20.04) 9.2

What did you do?

When using

db.SetConnMaxIdleTime(5 * time.Second)
db.SetConnMaxLifetime(5 * time.Hour)

idle connections get closed after 5 hours. While setting the parameters in reverse order works fine.

db.SetConnMaxLifetime(5 * time.Hour)
db.SetConnMaxIdleTime(5 * time.Second)

What did you expect to see?

Closing idle connections after ~5s.

What did you see instead?

Closing connections after ~5h

I think this is due to sql.go#L1041 only checking if maxIdleTime has been reduced and not also if its smaller than maxLifetime.

[seankhliao]

@Equinox76 both lines look the same?

[eqinox76]

Thanks! Copy paste error which i corrected.

[seankhliao]

cc @bradfitz @kardianos @kevinburke