When running Session.WithTransaction, the BAAS team are seeing data being committed to the database despite a context cancelation.

The BAAS team is issuing the transaction with the code here: https://github.com/rukumar333/baas/blob/BAAS-24930/realm/sync/server/transactionbroker/registry.go#L414

The error being returned by the WithTransaction is

context canceled

The BAAS team uses this fork of the Go Driver in production: https://github.com/mongodb-forks/mongo-go-driver/tree/release/v1.10.7-baas

Edit:

Pairing with rushil.kumar@mongodb.com , we can re-create the issue by adding the following code above the "CommitLoop" on either the BAAS fork or the v1 Go Driver branch:

		ctx, cancel := context.WithCancel(ctx)
		go func() {
			fmt.Println("timer started")
			timer := time.NewTimer(time.Duration(10 * time.Millisecond))

			select {
			case <-timer.C:
				fmt.Println("cancel")
				cancel()
			}
		}() 

This will result in errors such as the following:

canceled while checking out a connection from connection pool: context canceled; total connections: 0, maxPoolSize: 100, idle connections: 0, wait duration: 250ns 

The Go Driver documentation for Session.WithTransaction notes that you should not use the method with a cancelable context:

Because this method must succeed to ensure that server-side resources are properly cleaned up, context deadlines and cancellations will not be respected during this call.

Open question for triage: Is this a Go Driver bug?