kv: deflake raceTransport after pass-by-ref BatchRequest

pkg/kv/kvclient/kvcoord/dist_sender.go

@@ -1934,13 +1934,11 @@ func noMoreReplicasErr(ambiguousErr, lastAttemptErr error) error {
 func (ds *DistSender) sendToReplicas(
 	ctx context.Context, ba *roachpb.BatchRequest, routing rangecache.EvictionToken, withCommit bool,
 ) (*roachpb.BatchResponse, error) {
-	desc := routing.Desc()
-	ba.RangeID = desc.RangeID
-
 	// If this request can be sent to a follower to perform a consistent follower
 	// read under the closed timestamp, promote its routing policy to NEAREST.
 	if ba.RoutingPolicy == roachpb.RoutingPolicy_LEASEHOLDER &&
 		CanSendToFollower(ds.logicalClusterID.Get(), ds.st, ds.clock, routing.ClosedTimestampPolicy(), ba) {
+		ba = ba.ShallowCopy()
 		ba.RoutingPolicy = roachpb.RoutingPolicy_NEAREST
 	}
 
@@ -1956,6 +1954,7 @@ func (ds *DistSender) sendToReplicas(
 	default:
 		log.Fatalf(ctx, "unknown routing policy: %s", ba.RoutingPolicy)
 	}
+	desc := routing.Desc()
 	leaseholder := routing.Leaseholder()
 	replicas, err := NewReplicaSlice(ctx, ds.nodeDescs, desc, leaseholder, replicaFilter)
 	if err != nil {
@@ -2057,6 +2056,10 @@ func (ds *DistSender) sendToReplicas(
 			}
 		}
 		prevReplica = curReplica
+
+		ba = ba.ShallowCopy()
+		ba.Replica = curReplica
+		ba.RangeID = desc.RangeID
 		// Communicate to the server the information our cache has about the
 		// range. If it's stale, the serve will return an update.
 		ba.ClientRangeInfo = roachpb.ClientRangeInfo{

pkg/kv/kvclient/kvcoord/transport.go

@@ -185,8 +185,6 @@ func (gt *grpcTransport) SendNext(
 	if err != nil {
 		return nil, err
 	}
-
-	ba.Replica = r
 	return gt.sendBatch(ctx, r.NodeID, iface, ba)
 }
 

pkg/kv/kvclient/kvcoord/transport_race.go

@@ -54,7 +54,7 @@ type raceTransport struct {
 }
 
 func (tr raceTransport) SendNext(
-	ctx context.Context, ba roachpb.BatchRequest,
+	ctx context.Context, ba *roachpb.BatchRequest,
 ) (*roachpb.BatchResponse, error) {
 	// Make a copy of the requests slice, and shallow copies of the requests.
 	// The caller is allowed to mutate the request after the call returns. Since
@@ -69,10 +69,7 @@ func (tr raceTransport) SendNext(
 	}
 	ba.Requests = requestsCopy
 	select {
-	// We have a shallow copy here and so the top level scalar fields can't
-	// really race, but making more copies doesn't make anything more
-	// transparent, so from now on we operate on a pointer.
-	case incoming <- &ba:
+	case incoming <- ba:
 	default:
 		// Avoid slowing down the tests if we're backed up.
 	}

pkg/rpc/nodedialer/nodedialer.go

@@ -308,11 +308,12 @@ type TracingInternalClient struct {
 
 // Batch overrides the Batch RPC client method and fills in tracing information.
 func (tic TracingInternalClient) Batch(
-	ctx context.Context, req *roachpb.BatchRequest, opts ...grpc.CallOption,
+	ctx context.Context, ba *roachpb.BatchRequest, opts ...grpc.CallOption,
 ) (*roachpb.BatchResponse, error) {
 	sp := tracing.SpanFromContext(ctx)
 	if sp != nil && !sp.IsNoop() {
-		req.TraceInfo = sp.Meta().ToProto()
+		ba = ba.ShallowCopy()
+		ba.TraceInfo = sp.Meta().ToProto()
 	}
-	return tic.InternalClient.Batch(ctx, req, opts...)
+	return tic.InternalClient.Batch(ctx, ba, opts...)
 }