Merge pull request #17043 from machine424/ffl

chore: allow seamless use of testing/synctest for >=go1.24

.github/workflows/ci.yml

@@ -53,6 +53,8 @@ jobs:
     env:
       # Enforce the Go version.
       GOTOOLCHAIN: local
+      # TODO: remove once 1.25 is the min version.
+      GOEXPERIMENT: synctest
     container:
       # The go version in this image should be N-1 wrt test_go.
       image: quay.io/prometheus/golang-builder:1.24-base
@@ -63,6 +65,9 @@ jobs:
       - run: make build
       # Don't run NPM build; don't run race-detector.
       - run: make test GO_ONLY=1 test-flags=""
+      # TODO: remove once 1.25 is the min version.
+      # ensure we can build without the tag.
+      - run: GOEXPERIMENT="" make build
 
   test_ui:
     name: UI tests
@@ -229,15 +234,16 @@ jobs:
       - name: Get golangci-lint version
         id: golangci-lint-version
         run: echo "version=$(make print-golangci-lint-version)" >> $GITHUB_OUTPUT
-      - name: Lint with stringlabels
+      - name: Lint
         uses: golangci/golangci-lint-action@4afd733a84b1f43292c63897423277bb7f4313a9 # v8.0.0
         with:
-          args: --verbose --build-tags=stringlabels
+          args: --verbose
           version: ${{ steps.golangci-lint-version.outputs.version }}
       - name: Lint with slicelabels
         uses: golangci/golangci-lint-action@4afd733a84b1f43292c63897423277bb7f4313a9 # v8.0.0
         with:
-          args: --verbose --build-tags=slicelabels
+          # goexperiment.synctest to ensure we don't miss files that depend on it.
+          args: --verbose --build-tags=slicelabels,goexperiment.synctest
           version: ${{ steps.golangci-lint-version.outputs.version }}
       - name: Lint with dedupelabels
         uses: golangci/golangci-lint-action@4afd733a84b1f43292c63897423277bb7f4313a9 # v8.0.0

storage/remote/queue_manager.go

@@ -962,10 +962,10 @@ func (t *QueueManager) Stop() {
 	defer t.logger.Info("Remote storage stopped.")
 
 	close(t.quit)
-	t.wg.Wait()
 	// Wait for all QueueManager routines to end before stopping shards, metadata watcher, and WAL watcher. This
 	// is to ensure we don't end up executing a reshard and shards.stop() at the same time, which
 	// causes a closed channel panic.
+	t.wg.Wait()
 	t.shards.stop()
 	t.watcher.Stop()
 	if t.mcfg.Send {
@@ -1458,9 +1458,15 @@ func (q *queue) ReturnForReuse(batch []timeSeries) {
 // FlushAndShutdown stops the queue and flushes any samples. No appends can be
 // made after this is called.
 func (q *queue) FlushAndShutdown(done <-chan struct{}) {
+loop:
 	for q.tryEnqueueingBatch(done) {
-		time.Sleep(time.Second)
+		select {
+		case <-done:
+			break loop
+		case <-time.After(time.Second):
 		}
+	}
+
 	q.batchMtx.Lock()
 	defer q.batchMtx.Unlock()
 	q.batch = nil

storage/remote/queue_manager_test.go

@@ -49,6 +49,7 @@ import (
 	"github.com/prometheus/prometheus/util/compression"
 	"github.com/prometheus/prometheus/util/runutil"
 	"github.com/prometheus/prometheus/util/testutil"
+	"github.com/prometheus/prometheus/util/testutil/synctest"
 )
 
 const defaultFlushDeadline = 1 * time.Minute
@@ -456,8 +457,9 @@ func TestSampleDeliveryOrder(t *testing.T) {
 }
 
 func TestShutdown(t *testing.T) {
-	// Not t.Parallel() because the test became flaky; see https://github.com/prometheus/prometheus/issues/17045
+	t.Parallel()
-	deadline := 1 * time.Second
+	synctest.Test(t, func(t *testing.T) {
+		deadline := 15 * time.Second
 		c := NewTestBlockedWriteClient()
 
 		cfg := config.DefaultQueueConfig
@@ -473,7 +475,7 @@ func TestShutdown(t *testing.T) {
 		go func() {
 			m.Append(samples)
 		}()
-	time.Sleep(100 * time.Millisecond)
+		synctest.Wait()
 
 		// Test to ensure that Stop doesn't block.
 		start := time.Now()
@@ -481,13 +483,8 @@ func TestShutdown(t *testing.T) {
 		// The samples will never be delivered, so duration should
 		// be at least equal to deadline, otherwise the flush deadline
 		// was not respected.
-	duration := time.Since(start)
+		require.Equal(t, time.Since(start), deadline)
-	if duration > deadline+(deadline/10) {
+	})
-		t.Errorf("Took too long to shutdown: %s > %s", duration, deadline)
-	}
-	if duration < deadline {
-		t.Errorf("Shutdown occurred before flush deadline: %s < %s", duration, deadline)
-	}
 }
 
 func TestSeriesReset(t *testing.T) {

util/testutil/synctest/disabled.go

@@ -0,0 +1,29 @@
+// Copyright 2025 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//go:build !goexperiment.synctest && !go1.25
+
+package synctest
+
+import (
+	"testing"
+)
+
+func Test(t *testing.T, f func(t *testing.T)) {
+	t.Skip("goexperiment.synctest is not enabled")
+}
+
+func Wait() {
+	// It isn't meant to be called outside of Test().
+	panic("goexperiment.synctest is not enabled")
+}

util/testutil/synctest/enabled.go

@@ -0,0 +1,31 @@
+// Copyright 2025 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//go:build goexperiment.synctest && !go1.25
+
+package synctest
+
+import (
+	"testing"
+	"testing/synctest"
+)
+
+func Test(t *testing.T, f func(t *testing.T)) {
+	synctest.Run(func() {
+		f(t)
+	})
+}
+
+func Wait() {
+	synctest.Wait()
+}

util/testutil/synctest/synctest.go

@@ -0,0 +1,29 @@
+// Copyright 2025 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//go:build go1.25
+
+package synctest
+
+import (
+	"testing"
+	"testing/synctest"
+)
+
+func Test(t *testing.T, f func(t *testing.T)) {
+	synctest.Test(t, f)
+}
+
+func Wait() {
+	synctest.Wait()
+}