@@ -61,7 +61,7 @@ require (

 	github.com/miekg/dns v1.1.43

 	github.com/mistifyio/go-zfs/v3 v3.0.1

 	github.com/mitchellh/copystructure v1.2.0

-	github.com/moby/buildkit v0.12.3

+	github.com/moby/buildkit v0.12.4

 	github.com/moby/ipvs v1.1.0

 	github.com/moby/locker v1.0.1

 	github.com/moby/patternmatcher v0.6.0

@@ -912,8 +912,8 @@ github.com/mitchellh/reflectwalk v1.0.2 h1:G2LzWKi524PWgd3mLHV8Y5k7s6XUvT0Gef6zx

 github.com/mitchellh/reflectwalk v1.0.2/go.mod h1:mSTlrgnPZtwu0c4WaC2kGObEpuNDbx0jmZXqmk4esnw=

 github.com/mndrix/tap-go v0.0.0-20171203230836-629fa407e90b/go.mod h1:pzzDgJWZ34fGzaAZGFW22KVZDfyrYW+QABMrWnJBnSs=

 github.com/moby/buildkit v0.8.1/go.mod h1:/kyU1hKy/aYCuP39GZA9MaKioovHku57N6cqlKZIaiQ=

-github.com/moby/buildkit v0.12.3 h1:cFaPVnyC0PwAP5xHHfzdU5v9rgQrCi6HnGSg3WuFKp4=

-github.com/moby/buildkit v0.12.3/go.mod h1:adB4y0SxxX8trnrY+oEulb48ODLqPO6pKMF0ppGcCoI=

+github.com/moby/buildkit v0.12.4 h1:yKZDsObXLKarXqUx7YMnaB+TKv810bBhq0XLFWbkjT0=

+github.com/moby/buildkit v0.12.4/go.mod h1:XG74uz06nPWQpnxYwgCryrVidvor0+ElUxGosbZPQG4=

 github.com/moby/ipvs v1.1.0 h1:ONN4pGaZQgAx+1Scz5RvWV4Q7Gb+mvfRh3NsPS+1XQQ=

 github.com/moby/ipvs v1.1.0/go.mod h1:4VJMWuf098bsUMmZEiD4Tjk/O7mOn3l1PTD3s4OoYAs=

 github.com/moby/locker v1.0.1 h1:fOXqR41zeveg4fFODix+1Ch4mj/gT0NE1XJbp/epuBg=

@@ -55,15 +55,17 @@ func (ck *CacheKey) Output() Index {

 }

 func (ck *CacheKey) clone() *CacheKey {

+	ck.mu.RLock()

 	nk := &CacheKey{

 		ID:     ck.ID,

 		digest: ck.digest,

 		vtx:    ck.vtx,

 		output: ck.output,

-		ids:    map[*cacheManager]string{},

+		ids:    make(map[*cacheManager]string, len(ck.ids)),

 	}

 	for cm, id := range ck.ids {

 		nk.ids[cm] = id

 	}

+	ck.mu.RUnlock()

 	return nk

 }

@@ -101,34 +101,41 @@ func (cm *combinedCacheManager) Save(key *CacheKey, s Result, createdAt time.Tim

 }

 func (cm *combinedCacheManager) Records(ctx context.Context, ck *CacheKey) ([]*CacheRecord, error) {

+	ck.mu.RLock()

 	if len(ck.ids) == 0 {

+		ck.mu.RUnlock()

 		return nil, errors.Errorf("no results")

 	}

+	cms := make([]*cacheManager, 0, len(ck.ids))

+	for cm := range ck.ids {

+		cms = append(cms, cm)

+	}

+	ck.mu.RUnlock()

+

 	records := map[string]*CacheRecord{}

 	var mu sync.Mutex

 	eg, _ := errgroup.WithContext(context.TODO())

-	for c := range ck.ids {

-		func(c *cacheManager) {

-			eg.Go(func() error {

-				recs, err := c.Records(ctx, ck)

-				if err != nil {

-					return err

-				}

-				mu.Lock()

-				for _, rec := range recs {

-					if _, ok := records[rec.ID]; !ok || c == cm.main {

-						if c == cm.main {

-							rec.Priority = 1

-						}

-						records[rec.ID] = rec

+	for _, c := range cms {

+		c := c

+		eg.Go(func() error {

+			recs, err := c.Records(ctx, ck)

+			if err != nil {

+				return err

+			}

+			mu.Lock()

+			for _, rec := range recs {

+				if _, ok := records[rec.ID]; !ok || c == cm.main {

+					if c == cm.main {

+						rec.Priority = 1

 					}

+					records[rec.ID] = rec

 				}

-				mu.Unlock()

-				return nil

-			})

-		}(c)

+			}

+			mu.Unlock()

+			return nil

+		})

 	}

 	if err := eg.Wait(); err != nil {

@@ -85,8 +85,9 @@ func (e *exporter) ExportTo(ctx context.Context, t CacheExporterTarget, opt Cach

 		r        CacheExporterRecord

 		selector digest.Digest

 	}

+	k := e.k.clone() // protect against *CacheKey internal ids mutation from other exports

-	recKey := rootKey(e.k.Digest(), e.k.Output())

+	recKey := rootKey(k.Digest(), k.Output())

 	rec := t.Add(recKey)

 	allRec := []CacheExporterRecord{rec}

@@ -97,7 +98,7 @@ func (e *exporter) ExportTo(ctx context.Context, t CacheExporterTarget, opt Cach

 	}

 	exportRecord := opt.ExportRoots

-	if len(e.k.Deps()) > 0 {

+	if len(deps) > 0 {

 		exportRecord = true

 	}

@@ -126,7 +127,7 @@ func (e *exporter) ExportTo(ctx context.Context, t CacheExporterTarget, opt Cach

 		if opt.CompressionOpt != nil {

 			for _, r := range remotes { // record all remaining remotes as well

 				rec := t.Add(recKey)

-				rec.AddResult(e.k.vtx, int(e.k.output), v.CreatedAt, r)

+				rec.AddResult(k.vtx, int(k.output), v.CreatedAt, r)

 				variants = append(variants, rec)

 			}

 		}

@@ -147,7 +148,7 @@ func (e *exporter) ExportTo(ctx context.Context, t CacheExporterTarget, opt Cach

 			if opt.CompressionOpt != nil {

 				for _, r := range remotes { // record all remaining remotes as well

 					rec := t.Add(recKey)

-					rec.AddResult(e.k.vtx, int(e.k.output), v.CreatedAt, r)

+					rec.AddResult(k.vtx, int(k.output), v.CreatedAt, r)

 					variants = append(variants, rec)

 				}

 			}

@@ -155,7 +156,7 @@ func (e *exporter) ExportTo(ctx context.Context, t CacheExporterTarget, opt Cach

 		if remote != nil {

 			for _, rec := range allRec {

-				rec.AddResult(e.k.vtx, int(e.k.output), v.CreatedAt, remote)

+				rec.AddResult(k.vtx, int(k.output), v.CreatedAt, remote)

 			}

 		}

 		allRec = append(allRec, variants...)

@@ -198,7 +199,7 @@ func (e *exporter) ExportTo(ctx context.Context, t CacheExporterTarget, opt Cach

 			}

 		}

-		for cm, id := range e.k.ids {

+		for cm, id := range k.ids {

 			if _, err := addBacklinks(t, rec, cm, id, bkm); err != nil {

 				return nil, err

 			}

@@ -762,6 +762,9 @@ func (h *HistoryQueue) Listen(ctx context.Context, req *controlapi.BuildHistoryR

 		}()

 	}

+	// make a copy of events for active builds so we don't keep a lock during grpc send

+	actives := make([]*controlapi.BuildHistoryEvent, 0, len(h.active))

+

 	for _, e := range h.active {

 		if req.Ref != "" && e.Ref != req.Ref {

 			continue

@@ -769,7 +772,7 @@ func (h *HistoryQueue) Listen(ctx context.Context, req *controlapi.BuildHistoryR

 		if _, ok := h.deleted[e.Ref]; ok {

 			continue

 		}

-		sub.send(&controlapi.BuildHistoryEvent{

+		actives = append(actives, &controlapi.BuildHistoryEvent{

 			Type:   controlapi.BuildHistoryEventType_STARTED,

 			Record: e,

 		})

@@ -777,6 +780,12 @@ func (h *HistoryQueue) Listen(ctx context.Context, req *controlapi.BuildHistoryR

 	h.mu.Unlock()

+	for _, e := range actives {

+		if err := f(e); err != nil {

+			return err

+		}

+	}

+

 	if !req.ActiveOnly {

 		events := []*controlapi.BuildHistoryEvent{}

 		if err := h.opt.DB.View(func(tx *bolt.Tx) error {

@@ -810,7 +819,7 @@ func (h *HistoryQueue) Listen(ctx context.Context, req *controlapi.BuildHistoryR

 		}

 		h.mu.Unlock()

 		for _, e := range events {

-			if e.Record == nil {

+			if e == nil || e.Record == nil {

 				continue

 			}

 			if err := f(e); err != nil {

@@ -680,7 +680,7 @@ github.com/mitchellh/hashstructure/v2

 # github.com/mitchellh/reflectwalk v1.0.2

 ## explicit

 github.com/mitchellh/reflectwalk

-# github.com/moby/buildkit v0.12.3

+# github.com/moby/buildkit v0.12.4

 ## explicit; go 1.20

 github.com/moby/buildkit/api/services/control

 github.com/moby/buildkit/api/types