diff --git a/api/v3/rpc.go b/api/v3/rpc.go
index 9a7cae74..2be2863b 100644
--- a/api/v3/rpc.go
+++ b/api/v3/rpc.go
@@ -15,7 +15,10 @@
 package v3
 
 import (
+	"sync"
+
 	"golang.org/x/net/context"
+	"golang.org/x/sync/errgroup"
 	"google.golang.org/grpc/codes"
 	"google.golang.org/grpc/status"
 
@@ -83,32 +86,47 @@ func (s *AncestryServer) PostAncestry(ctx context.Context, req *pb.PostAncestryR
 	}
 
 	builder := clair.NewAncestryBuilder(clair.EnabledDetectors())
-	for _, layer := range req.Layers {
-		if layer == nil {
-			err := status.Error(codes.InvalidArgument, "ancestry layer is invalid")
-			return nil, err
-		}
-
-		if layer.GetHash() == "" {
-			return nil, status.Error(codes.InvalidArgument, "ancestry layer hash should not be empty")
-		}
-
-		if layer.GetPath() == "" {
-			return nil, status.Error(codes.InvalidArgument, "ancestry layer path should not be empty")
+	layerMap := map[string]*database.Layer{}
+	layerMapLock := sync.RWMutex{}
+	g, analyzerCtx := errgroup.WithContext(ctx)
+	for i := range req.Layers {
+		layer := req.Layers[i]
+		if _, ok := layerMap[layer.Hash]; !ok {
+			layerMap[layer.Hash] = nil
+			if layer == nil {
+				err := status.Error(codes.InvalidArgument, "ancestry layer is invalid")
+				return nil, err
+			}
+
+			if layer.GetHash() == "" {
+				return nil, status.Error(codes.InvalidArgument, "ancestry layer hash should not be empty")
+			}
+
+			if layer.GetPath() == "" {
+				return nil, status.Error(codes.InvalidArgument, "ancestry layer path should not be empty")
+			}
+
+			g.Go(func() error {
+				clairLayer, err := clair.AnalyzeLayer(analyzerCtx, s.Store, layer.Hash, req.Format, layer.Path, layer.Headers)
+				if err != nil {
+					return err
+				}
+
+				layerMapLock.Lock()
+				layerMap[layer.Hash] = clairLayer
+				layerMapLock.Unlock()
+
+				return nil
+			})
 		}
+	}
 
-		// TODO(sidac): make AnalyzeLayer to be async to ensure
-		// non-blocking downloads.
-		// We'll need to deal with two layers post by the same or different
-		// requests that may have the same hash. In that case, since every
-		// layer/feature/namespace is unique in the database, it may introduce
-		// deadlock.
-		clairLayer, err := clair.AnalyzeLayer(ctx, s.Store, layer.Hash, req.Format, layer.Path, layer.Headers)
-		if err != nil {
-			return nil, newRPCErrorWithClairError(codes.Internal, err)
-		}
+	if err = g.Wait(); err != nil {
+		return nil, newRPCErrorWithClairError(codes.Internal, err)
+	}
 
-		builder.AddLeafLayer(clairLayer)
+	for _, layer := range req.Layers {
+		builder.AddLeafLayer(layerMap[layer.Hash])
 	}
 
 	if err := clair.SaveAncestry(s.Store, builder.Ancestry(req.AncestryName)); err != nil {