Data Race in Connection Pool #141
Description
We've recently been running using the connection pool and discovered a data race. Running the following snippet:
func main() {
auth := <auth code here>
pool, err := email.NewPool(
"<address here>", 4, auth)
if err != nil {
panic(fmt.Errorf("failed to create email pool: %v", err))
}
var wg sync.WaitGroup
n := 10
wg.Add(n)
for i := 0; i < n; i++ {
go func() {
var err error
err = pool.Send(&email.Email{
To: []string{"[email protected]"},
From: "[email protected]",
Text: []byte("This is a test"),
}, time.Second*10)
if err != nil {
panic(err)
}
wg.Done()
}()
}
wg.Wait()
}With the Go race detector enabled:
go run -race main.go
Yields error messages like:
==================
WARNING: DATA RACE
Read at 0x00c0000d6028 by goroutine 12:
github.com/jordan-wright/email.(*Pool).get()
/Users/dndawso/go/pkg/mod/github.com/jordan-wright/[email protected]+incompatible/pool.go:87 +0xac
github.com/jordan-wright/email.(*Pool).Send()
/Users/dndawso/go/pkg/mod/github.com/jordan-wright/[email protected]+incompatible/pool.go:283 +0x95
main.main.func1()
/Users/dndawso/repos/emailtest/main.go:80 +0x244
Previous write at 0x00c0000d6028 by goroutine 10:
github.com/jordan-wright/email.(*Pool).inc()
/Users/dndawso/go/pkg/mod/github.com/jordan-wright/[email protected]+incompatible/pool.go:155 +0x191
github.com/jordan-wright/email.(*Pool).makeOne.func1()
/Users/dndawso/go/pkg/mod/github.com/jordan-wright/[email protected]+incompatible/pool.go:172 +0x3c
Goroutine 12 (running) created at:
main.main()
/Users/dndawso/repos/emailtest/main.go:77 +0x205
Goroutine 10 (running) created at:
github.com/jordan-wright/email.(*Pool).makeOne()
/Users/dndawso/go/pkg/mod/github.com/jordan-wright/[email protected]+incompatible/pool.go:171 +0x4c
github.com/jordan-wright/email.(*Pool).get()
/Users/dndawso/go/pkg/mod/github.com/jordan-wright/[email protected]+incompatible/pool.go:88 +0x34d
github.com/jordan-wright/email.(*Pool).Send()
/Users/dndawso/go/pkg/mod/github.com/jordan-wright/[email protected]+incompatible/pool.go:283 +0x95
main.main.func1()
/Users/dndawso/repos/emailtest/main.go:80 +0x244
==================
I believe I see the culprit (references to p.created without locking p.mut) and will work on a pull request.