Merge pull request #13135 from machine424/race-ww

remote-write: fix race condition between ApplyConfig and Notify

storage/remote/storage.go

@@ -77,10 +77,7 @@ func NewStorage(l log.Logger, reg prometheus.Registerer, stCallback startTimeCal
 }
 
 func (s *Storage) Notify() {
-	for _, q := range s.rws.queues {
-		// These should all be non blocking
-		q.watcher.Notify()
-	}
+	s.rws.Notify()
 }
 
 // ApplyConfig updates the state as the new config requires.

storage/remote/storage_test.go

@@ -14,7 +14,9 @@
 package remote
 
 import (
+	"fmt"
 	"net/url"
+	"sync"
 	"testing"
 
 	common_config "github.com/prometheus/common/config"
@@ -147,3 +149,39 @@ func baseRemoteReadConfig(host string) *config.RemoteReadConfig {
 	}
 	return &cfg
 }
+
+// TestWriteStorageApplyConfigsDuringCommit helps detecting races when
+// ApplyConfig runs concurrently with Notify
+// See https://github.com/prometheus/prometheus/issues/12747
+func TestWriteStorageApplyConfigsDuringCommit(t *testing.T) {
+	s := NewStorage(nil, nil, nil, t.TempDir(), defaultFlushDeadline, nil)
+
+	var wg sync.WaitGroup
+	wg.Add(2000)
+
+	start := make(chan struct{})
+	for i := 0; i < 1000; i++ {
+		go func(i int) {
+			<-start
+			conf := &config.Config{
+				GlobalConfig: config.DefaultGlobalConfig,
+				RemoteWriteConfigs: []*config.RemoteWriteConfig{
+					baseRemoteWriteConfig(fmt.Sprintf("http://test-%d.com", i)),
+				},
+			}
+			require.NoError(t, s.ApplyConfig(conf))
+			wg.Done()
+		}(i)
+	}
+
+	for i := 0; i < 1000; i++ {
+		go func() {
+			<-start
+			s.Notify()
+			wg.Done()
+		}()
+	}
+
+	close(start)
+	wg.Wait()
+}

storage/remote/write.go

@@ -121,6 +121,16 @@ func (rws *WriteStorage) run() {
 	}
 }
 
+func (rws *WriteStorage) Notify() {
+	rws.mtx.Lock()
+	defer rws.mtx.Unlock()
+
+	for _, q := range rws.queues {
+		// These should all be non blocking
+		q.watcher.Notify()
+	}
+}
+
 // ApplyConfig updates the state as the new config requires.
 // Only stop & create queues which have changes.
 func (rws *WriteStorage) ApplyConfig(conf *config.Config) error {