TracerProvider ForceFlush() Error Fix

CHANGELOG.md

@@ -15,6 +15,10 @@ The next release will require at least [Go 1.25].
 
 - Support testing of [Go 1.26]. (#7902)
 
+### Changed
+
+- `TracerProvider.ForceFlush` in `go.opentelemetry.io/otel/sdk/trace` joins errors together and continues iteration through SpanProcessors as opposed to returning the first encountered error without attempting exports on subsequent SpanProcessors. (#7856)
+
 <!-- Released section -->
 <!-- Don't change this section unless doing release -->
 

sdk/trace/provider.go

@@ -5,6 +5,7 @@ package trace // import "go.opentelemetry.io/otel/sdk/trace"
 
 import (
 	"context"
+	"errors"
 	"fmt"
 	"sync"
 	"sync/atomic"
@@ -262,18 +263,17 @@ func (p *TracerProvider) ForceFlush(ctx context.Context) error {
 		return nil
 	}
 
+	var err error
 	for _, sps := range spss {
 		select {
 		case <-ctx.Done():
 			return ctx.Err()
 		default:
 		}
 
-		if err := sps.sp.ForceFlush(ctx); err != nil {
-			return err
-		}
+		err = errors.Join(err, sps.sp.ForceFlush(ctx))
 	}
-	return nil
+	return err
 }
 
 // Shutdown shuts down TracerProvider. All registered span processors are shut down

sdk/trace/provider_test.go

@@ -28,6 +28,7 @@ type basicSpanProcessor struct {
 	flushed             bool
 	closed              bool
 	injectShutdownError error
+	injectExportError   error
 }
 
 func (t *basicSpanProcessor) Shutdown(context.Context) error {
@@ -38,6 +39,10 @@ func (t *basicSpanProcessor) Shutdown(context.Context) error {
 func (*basicSpanProcessor) OnStart(context.Context, ReadWriteSpan) {}
 func (*basicSpanProcessor) OnEnd(ReadOnlySpan)                     {}
 func (t *basicSpanProcessor) ForceFlush(context.Context) error {
+	if t.injectExportError != nil {
+		t.flushed = false
+		return t.injectExportError
+	}
 	t.flushed = true
 	return nil
 }
@@ -227,6 +232,60 @@ func TestRegisterAfterShutdownWithProcessors(t *testing.T) {
 	assert.Empty(t, stp.getSpanProcessors())
 }
 
+func TestTracerProviderForceFlush(t *testing.T) {
+	t.Run("AfterShutdown", func(t *testing.T) {
+		stp := NewTracerProvider()
+		sp1 := &basicSpanProcessor{}
+		stp.RegisterSpanProcessor(sp1)
+		ctx := t.Context()
+
+		require.NoError(t, stp.ForceFlush(ctx))
+		require.True(t, sp1.flushed, "SpanProcessor ForceFlush not called")
+
+		sp1.flushed = false
+		require.NoError(t, stp.Shutdown(ctx))
+
+		require.NoError(t, stp.ForceFlush(ctx))
+		assert.False(t, sp1.flushed, "SpanProcessor ForceFlush called after Shutdown")
+	})
+
+	t.Run("Multi", func(t *testing.T) {
+		stp := NewTracerProvider()
+		sp1 := &basicSpanProcessor{}
+		sp2 := &basicSpanProcessor{}
+		stp.RegisterSpanProcessor(sp1)
+		stp.RegisterSpanProcessor(sp2)
+		ctx := t.Context()
+
+		require.NoError(t, stp.ForceFlush(ctx))
+		require.True(t, sp1.flushed, "SpanProcessor ForceFlush not called")
+		require.True(t, sp2.flushed, "SpanProcessor ForceFlush not called")
+	})
+
+	t.Run("MultiWithSPError", func(t *testing.T) {
+		stp := NewTracerProvider()
+		spErr := errors.New("basic span processor export failure")
+		sp1 := &basicSpanProcessor{injectExportError: spErr}
+		sp2 := &basicSpanProcessor{}
+		stp.RegisterSpanProcessor(sp1)
+		stp.RegisterSpanProcessor(sp2)
+		ctx := t.Context()
+
+		assert.ErrorIs(t, stp.ForceFlush(ctx), sp1.injectExportError, "span processor error not returned")
+		require.False(t, sp1.flushed, "SpanProcessor wrongly considered flushed")
+		require.True(t, sp2.flushed, "SpanProcessor ForceFlush not called")
+	})
+
+	t.Run("WithCancel", func(t *testing.T) {
+		stp := NewTracerProvider()
+		sp1 := &basicSpanProcessor{}
+		stp.RegisterSpanProcessor(sp1)
+		ctx, cancel := context.WithCancel(t.Context())
+		cancel()
+		assert.ErrorIs(t, stp.ForceFlush(ctx), context.Canceled)
+	})
+}
+
 func TestTracerProviderSamplerConfigFromEnv(t *testing.T) {
 	type testCase struct {
 		sampler             string