server: don't mix Tracers in test tenant

pkg/base/test_server_args.go

@@ -242,7 +242,6 @@ type TestTenantArgs struct {
 	// Settings allows the caller to control the settings object used for the
 	// tenant cluster.
 	Settings *cluster.Settings
-	Tracer   *tracing.Tracer
 
 	// AllowSettingClusterSettings, if true, allows the tenant to set in-memory
 	// cluster settings.

pkg/server/testserver.go

@@ -582,11 +582,21 @@ func (ts *TestServer) StartTenant(
 	if params.TempStorageConfig != nil {
 		sqlCfg.TempStorageConfig = *params.TempStorageConfig
 	}
-	tr := params.Tracer
-	if params.Tracer == nil {
-		tr = tracing.NewTracerWithOpt(ctx, tracing.WithClusterSettings(&st.SV))
-	}
-	baseCfg := makeTestBaseConfig(st, tr)
+
+	stopper := params.Stopper
+	if stopper == nil {
+		// We don't share the stopper with the server because we want their Tracers
+		// to be different, to simulate them being different processes.
+		tr := tracing.NewTracerWithOpt(ctx, tracing.WithClusterSettings(&st.SV))
+		stopper = stop.NewStopper(stop.WithTracer(tr))
+		// The server's stopper stops the tenant, for convenience.
+		ts.Stopper().AddCloser(stop.CloserFn(func() { stopper.Stop(context.Background()) }))
+	} else if stopper.Tracer() == nil {
+		tr := tracing.NewTracerWithOpt(ctx, tracing.WithClusterSettings(&st.SV))
+		stopper.SetTracer(tr)
+	}
+
+	baseCfg := makeTestBaseConfig(st, stopper.Tracer())
 	baseCfg.TestingKnobs = params.TestingKnobs
 	baseCfg.Insecure = params.ForceInsecure
 	baseCfg.Locality = params.Locality
@@ -603,10 +613,6 @@ func (ts *TestServer) StartTenant(
 			tenantKnobs.ClusterSettingsUpdater = st.MakeUpdater()
 		}
 	}
-	stopper := params.Stopper
-	if stopper == nil {
-		stopper = ts.Stopper()
-	}
 	sqlServer, addr, httpAddr, err := StartTenant(
 		ctx,
 		stopper,

pkg/util/stop/stopper.go

@@ -620,3 +620,8 @@ func (s *Stopper) Quiesce(ctx context.Context) {
 func (s *Stopper) SetTracer(tr *tracing.Tracer) {
 	s.tracer = tr
 }
+
+// Tracer returns the Tracer that the Stopper will use for tasks.
+func (s *Stopper) Tracer() *tracing.Tracer {
+	return s.tracer
+}