limit log vertex size with 1M to avoid huge grpc message making client buffer overflow

Signed-off-by: sunchunming <sunchunming1@jd.com>

control/control.go

@@ -333,8 +333,8 @@ func (c *Controller) Status(req *controlapi.StatusRequest, stream controlapi.Con
 				return nil
 			}
 			logSize := 0
-			retry := false
 			for {
+				retry := false
 				sr := controlapi.StatusResponse{}
 				for _, v := range ss.Vertexes {
 					sr.Vertexes = append(sr.Vertexes, &controlapi.Vertex{
@@ -366,7 +366,7 @@ func (c *Controller) Status(req *controlapi.StatusRequest, stream controlapi.Con
 						Msg:       v.Data,
 						Timestamp: v.Timestamp,
 					})
-					logSize += len(v.Data)
+					logSize += len(v.Data) + emptyLogVertexSize
 					// avoid logs growing big and split apart if they do
 					if logSize > 1024*1024 {
 						ss.Vertexes = nil

control/init.go

@@ -0,0 +1,10 @@
+package control
+
+import controlapi "github.com/moby/buildkit/api/services/control"
+
+var emptyLogVertexSize int
+
+func init() {
+	emptyLogVertex := controlapi.VertexLog{}
+	emptyLogVertexSize = emptyLogVertex.Size()
+}