Try to increase roomserver parallelisation

roomserver/internal/input/input.go

@@ -19,17 +19,16 @@ import (
 	"context"
 	"encoding/json"
 	"sync"
-	"time"
 
 	"github.com/Shopify/sarama"
 	"github.com/getsentry/sentry-go"
+	"github.com/matrix-org/dendrite/internal"
 	"github.com/matrix-org/dendrite/internal/hooks"
 	"github.com/matrix-org/dendrite/roomserver/acls"
 	"github.com/matrix-org/dendrite/roomserver/api"
 	"github.com/matrix-org/dendrite/roomserver/storage"
 	"github.com/matrix-org/gomatrixserverlib"
 	log "github.com/sirupsen/logrus"
-	"go.uber.org/atomic"
 )
 
 type Inputer struct {
@@ -38,41 +37,7 @@ type Inputer struct {
 	ServerName           gomatrixserverlib.ServerName
 	ACLs                 *acls.ServerACLs
 	OutputRoomEventTopic string
-
-	workers sync.Map // room ID -> *inputWorker
-}
-
-type inputTask struct {
-	ctx   context.Context
-	event *api.InputRoomEvent
-	wg    *sync.WaitGroup
-	err   error // written back by worker, only safe to read when all tasks are done
-}
-
-type inputWorker struct {
-	r       *Inputer
-	running atomic.Bool
-	input   chan *inputTask
-}
-
-// Guarded by a CAS on w.running
-func (w *inputWorker) start() {
-	defer w.running.Store(false)
-	for {
-		select {
-		case task := <-w.input:
-			hooks.Run(hooks.KindNewEventReceived, task.event.Event)
-			_, task.err = w.r.processRoomEvent(task.ctx, task.event)
-			if task.err == nil {
-				hooks.Run(hooks.KindNewEventPersisted, task.event.Event)
-			} else {
-				sentry.CaptureException(task.err)
-			}
-			task.wg.Done()
-		case <-time.After(time.Second * 5):
-			return
-		}
-	}
+	roomMutexes          internal.MutexByRoom
 }
 
 // WriteOutputEvents implements OutputRoomEventWriter
@@ -123,57 +88,38 @@ func (r *Inputer) InputRoomEvents(
 	request *api.InputRoomEventsRequest,
 	response *api.InputRoomEventsResponse,
 ) {
-	// Create a wait group. Each task that we dispatch will call Done on
-	// this wait group so that we know when all of our events have been
-	// processed.
+	ctx := context.Background()
+
 	wg := &sync.WaitGroup{}
+	errs := make(chan error)
 	wg.Add(len(request.InputRoomEvents))
-	tasks := make([]*inputTask, len(request.InputRoomEvents))
-
-	for i, e := range request.InputRoomEvents {
-		// Work out if we are running per-room workers or if we're just doing
-		// it on a global basis (e.g. SQLite).
-		roomID := "global"
-		if r.DB.SupportsConcurrentRoomInputs() {
-			roomID = e.Event.RoomID()
-		}
-
-		// Look up the worker, or create it if it doesn't exist. This channel
-		// is buffered to reduce the chance that we'll be blocked by another
-		// room - the channel will be quite small as it's just pointer types.
-		w, _ := r.workers.LoadOrStore(roomID, &inputWorker{
-			r:     r,
-			input: make(chan *inputTask, 32),
-		})
-		worker := w.(*inputWorker)
-
-		// Create a task. This contains the input event and a reference to
-		// the wait group, so that the worker can notify us when this specific
-		// task has been finished.
-		tasks[i] = &inputTask{
-			ctx:   context.Background(),
-			event: &request.InputRoomEvents[i],
-			wg:    wg,
-		}
-
-		// Send the task to the worker.
-		if worker.running.CAS(false, true) {
-			go worker.start()
-		}
-		worker.input <- tasks[i]
-	}
-
-	// Wait for all of the workers to return results about our tasks.
+	go func() {
 		wg.Wait()
+		close(errs)
+	}()
 
-	// If any of the tasks returned an error, we should probably report
-	// that back to the caller.
-	for _, task := range tasks {
-		if task.err != nil {
-			response.ErrMsg = task.err.Error()
-			_, rejected := task.err.(*gomatrixserverlib.NotAllowed)
+	for _, e := range request.InputRoomEvents {
+		go func(e *api.InputRoomEvent) {
+			defer wg.Done()
+			hooks.Run(hooks.KindNewEventReceived, e.Event)
+			_, err := r.processRoomEvent(ctx, e)
+			if err == nil {
+				hooks.Run(hooks.KindNewEventPersisted, e.Event)
+			} else {
+				sentry.CaptureException(err)
+				select {
+				case errs <- err:
+				default:
+				}
+			}
+		}(&e)
+	}
+
+	for err := range errs {
+		if err != nil {
+			response.ErrMsg = err.Error()
+			_, rejected := err.(*gomatrixserverlib.NotAllowed)
 			response.NotAllowed = rejected
-			return
 		}
 	}
 }

roomserver/internal/input/input_latest_events.go

@@ -288,6 +288,9 @@ func (u *latestEventsUpdater) calculateLatest(
 	newEvent *gomatrixserverlib.Event,
 	newStateAndRef types.StateAtEventAndReference,
 ) (bool, error) {
+	u.api.roomMutexes.Lock(u.event.EventID())
+	defer u.api.roomMutexes.Unlock(u.event.EventID())
+
 	// First of all, get a list of all of the events in our current
 	// set of forward extremities.
 	existingRefs := make(map[string]*types.StateAtEventAndReference)