A better error handling and test the case

output/cloud/expv2/flush.go

@@ -112,7 +112,11 @@ func (f *metricsFlusher) flushBatches(batches []metricSetBuilder) error {
 				default:
 				}
 				if err := f.push(chunk[i]); err != nil {
-					errs <- err
+					select {
+					case errs <- err:
+					case <-stop:
+						return
+					}
 				}
 			}
 		}(batches[offset:end])

output/cloud/expv2/flush_test.go

@@ -1,6 +1,7 @@
 package expv2
 
 import (
+	"errors"
 	"strconv"
 	"sync"
 	"sync/atomic"
@@ -39,6 +40,7 @@ func TestMetricSetBuilderAddTimeBucket(t *testing.T) {
 	require.Len(t, msb.MetricSet.Metrics, 1)
 	assert.Len(t, msb.MetricSet.Metrics[0].TimeSeries, 1)
 }
+
 func TestMetricsFlusherFlushInBatchWithinBucket(t *testing.T) {
 	t.Parallel()
 
@@ -89,11 +91,11 @@ func TestMetricsFlusherFlushInBatchAcrossBuckets(t *testing.T) {
 	t.Parallel()
 
 	testCases := []struct {
-		series        int
-		expFlushCalls int
+		series       int
+		expPushCalls int
 	}{
-		{series: 5, expFlushCalls: 2},
-		{series: 2, expFlushCalls: 1},
+		{series: 5, expPushCalls: 2},
+		{series: 2, expPushCalls: 1},
 	}
 
 	r := metrics.NewRegistry()
@@ -131,7 +133,7 @@ func TestMetricsFlusherFlushInBatchAcrossBuckets(t *testing.T) {
 
 		err := mf.flush()
 		require.NoError(t, err)
-		assert.Equal(t, tc.expFlushCalls, pm.timesCalled())
+		assert.Equal(t, tc.expPushCalls, pm.timesCalled())
 	}
 }
 
@@ -214,7 +216,10 @@ func TestFlushWithReservedLabels(t *testing.T) {
 }
 
 type pusherMock struct {
-	hook       func(*pbcloud.MetricSet)
+	// hook is called when the push method is called.
+	hook func(*pbcloud.MetricSet)
+	// errFn if this defined, it is called instead
+	errFn      func() error
 	pushCalled int64
 }
 
@@ -228,5 +233,61 @@ func (pm *pusherMock) push(ms *pbcloud.MetricSet) error {
 	}
 
 	atomic.AddInt64(&pm.pushCalled, 1)
+
+	if pm.errFn != nil {
+		return pm.errFn()
+	}
+
 	return nil
 }
+
+func TestMetricsFlusherErrorCase(t *testing.T) {
+	t.Parallel()
+
+	r := metrics.NewRegistry()
+	m1 := r.MustNewMetric("metric1", metrics.Counter)
+
+	logger, _ := testutils.NewLoggerWithHook(t)
+
+	bq := &bucketQ{}
+	pm := &pusherMock{
+		errFn: func() error {
+			return errors.New("some error")
+		},
+	}
+	mf := metricsFlusher{
+		bq:                   bq,
+		client:               pm,
+		logger:               logger,
+		discardedLabels:      make(map[string]struct{}),
+		maxSeriesInBatch:     3,
+		batchPushConcurrency: 2,
+	}
+
+	series := 7
+
+	bq.buckets = make([]timeBucket, 0, series)
+	for i := 0; i < series; i++ {
+		ts := metrics.TimeSeries{
+			Metric: m1,
+			Tags:   r.RootTagSet().With("key1", "val"+strconv.Itoa(i)),
+		}
+		bq.Push([]timeBucket{
+			{
+				Time: int64(i) + 1,
+				Sinks: map[metrics.TimeSeries]metricValue{
+					ts: &counter{Sum: float64(1)},
+				},
+			},
+		})
+	}
+	require.Len(t, bq.buckets, series)
+
+	err := mf.flush()
+	require.Error(t, err)
+	// since the push happens concurrently the number of the calls could vary,
+	// but at least one call should happen and it should be less than the
+	// batchPushConcurrency
+	assert.LessOrEqual(t, pm.timesCalled(), mf.batchPushConcurrency)
+	assert.GreaterOrEqual(t, pm.timesCalled(), 1)
+}

output/cloud/expv2/output.go

@@ -7,7 +7,6 @@ import (
 	"errors"
 	"fmt"
 	"net/http"
-	"runtime"
 	"strconv"
 	"sync"
 	"time"
@@ -115,8 +114,7 @@ func (o *Output) Start() error {
 		maxSeriesInBatch:           int(o.config.MaxTimeSeriesInBatch.Int64),
 		// TODO: when the migration from v1 is over
 		// change the default of cloudapi.MetricPushConcurrency to use GOMAXPROCS(0)
-		// batchPushConcurrency: int(o.config.MetricPushConcurrency.Int64),
-		batchPushConcurrency: runtime.GOMAXPROCS(0),
+		batchPushConcurrency: int(o.config.MetricPushConcurrency.Int64),
 	}
 
 	o.runFlushWorkers()
@@ -185,31 +183,25 @@ func (o *Output) StopWithTestError(_ error) error {
 func (o *Output) runFlushWorkers() {
 	t := time.NewTicker(o.config.MetricPushInterval.TimeDuration())
 
-	// TODO: drop it when we are sure of the new proposed architecture
-	// workers := o.config.MetricPushConcurrency.Int64
-	// Details: https://github.com/grafana/k6/issues/3192
-	workers := 1
+	o.wg.Add(1)
 
-	for i := 0; i < workers; i++ {
-		o.wg.Add(1)
-		go func() {
-			defer func() {
-				t.Stop()
-				o.wg.Done()
-			}()
+	go func() {
+		defer func() {
+			t.Stop()
+			o.wg.Done()
+		}()
 
-			for {
-				select {
-				case <-t.C:
-					o.flushMetrics()
-				case <-o.stop:
-					return
-				case <-o.abort:
-					return
-				}
+		for {
+			select {
+			case <-t.C:
+				o.flushMetrics()
+			case <-o.stop:
+				return
+			case <-o.abort:
+				return
 			}
-		}()
-	}
+		}
+	}()
 }
 
 // AddMetricSamples receives the samples streaming.

output/cloud/expv2/output_test.go

@@ -305,7 +305,7 @@ func TestOutputStopWithTestError(t *testing.T) {
 	require.NoError(t, o.StopWithTestError(errors.New("an error")))
 }
 
-func TestOutputFlushMetricsConcurrently(t *testing.T) {
+func TestOutputFlushTicks(t *testing.T) {
 	t.Parallel()
 
 	done := make(chan struct{})
@@ -321,12 +321,10 @@ func TestOutputFlushMetricsConcurrently(t *testing.T) {
 			close(done)
 			return
 		}
-		<-done
 	}
 
 	o := Output{logger: testutils.NewLogger(t)}
-	o.config.MetricPushConcurrency = null.IntFrom(2)
-	o.config.MetricPushInterval = types.NullDurationFrom(1) // loop
+	o.config.MetricPushInterval = types.NullDurationFrom(100 * time.Millisecond) // loop
 	o.flushing = flusherFunc(flusherMock)
 	o.runFlushWorkers()