diff --git a/server/operation.go b/server/operation.go
index 77c1944..0ba2541 100644
--- a/server/operation.go
+++ b/server/operation.go
@@ -8,6 +8,7 @@ import (
 	"sync"
 	"time"
 
+	"repositories.action2quare.com/ayo/gocommon/logger"
 	"repositories.action2quare.com/ayo/houston/shared"
 	"repositories.action2quare.com/ayo/houston/shared/protos"
 )
@@ -191,8 +192,14 @@ func (os *operationServer) Query(svr protos.Operation_QueryServer) error {
 		return err
 	}
 
+	hostname := desc.Hostname
 	key, opChan := os.hp.regist(desc)
-	defer os.hp.unregist(key)
+	defer func() {
+		logger.Println("operationServer.Query : houston client unregistered ", hostname)
+		os.hp.unregist(key)
+	}()
+
+	logger.Println("operationServer.Query : houston client registered ", hostname)
 
 Outer:
 	for {