Use BatchSpanProcessor instead of SimpleSpanProcessor (#24)

As reported by @milanaleksic, the launcher was configured to use the SimpleSpanProcessor
which was affecting application performance. This change updates the launcher to
configure the BatchSpanProcessor by default.

launcher/config.go

@@ -361,9 +361,10 @@ func setupTracing(c Config) (func() error, error) {
 		return nil, fmt.Errorf("failed to create span exporter: %v", err)
 	}
 
+	bsp := trace.NewBatchSpanProcessor(spanExporter)
 	tp := trace.NewTracerProvider(
 		trace.WithConfig(trace.Config{DefaultSampler: trace.AlwaysSample()}),
-		trace.WithSyncer(spanExporter),
+		trace.WithSpanProcessor(bsp),
 		trace.WithResource(c.Resource),
 	)
 
@@ -374,6 +375,7 @@ func setupTracing(c Config) (func() error, error) {
 	global.SetTracerProvider(tp)
 
 	return func() error {
+		bsp.Shutdown()
 		return spanExporter.Shutdown(context.Background())
 	}, nil
 }

launcher/config_test.go

@@ -449,7 +449,8 @@ func TestConfigurePropagators(t *testing.T) {
 	prop = global.TextMapPropagator()
 	prop.Inject(ctx, carrier)
 	assert.Greater(t, len(carrier.Get("x-b3-traceid")), 0)
-	assert.Equal(t, "keyone=foo1,keytwo=bar1", carrier.Get("otcorrelations"))
+	assert.Contains(t, carrier.Get("otcorrelations"), "keytwo=bar1")
+	assert.Contains(t, carrier.Get("otcorrelations"), "keyone=foo1")
 
 	logger = &testLogger{}
 	lsOtel = ConfigureOpentelemetry(