diff --git a/lualib-src/lua-skynet.c b/lualib-src/lua-skynet.c
index 1e76ab62..4e23233d 100644
--- a/lualib-src/lua-skynet.c
+++ b/lualib-src/lua-skynet.c
@@ -309,7 +309,7 @@ _send(lua_State *L) {
 	if (session < 0) {
 		// send to invalid address
 		// todo: maybe throw error is better
-		session = 0;
+		return 0;
 	}
 	lua_pushinteger(L,session);
 	return 1;
diff --git a/lualib/skynet.lua b/lualib/skynet.lua
index e1b83650..8a26ac1a 100644
--- a/lualib/skynet.lua
+++ b/lualib/skynet.lua
@@ -233,20 +233,24 @@ skynet.tostring = assert(c.tostring)
 function skynet.call(addr, typename, ...)
 	local p = proto[typename]
 	local session = c.send(addr, p.id , nil , p.pack(...))
-	return p.unpack(coroutine_yield("CALL", session))
+	return p.unpack(coroutine_yield("CALL", assert(session, "call to invalid address")))
 end
 
 function skynet.blockcall(addr, typename , ...)
 	local p = proto[typename]
 	c.command("LOCK")
 	local session = c.send(addr, p.id , nil , p.pack(...))
+	if session == nil then
+		c.command("UNLOCK")
+		error("call to invalid address")
+	end
 	return p.unpack(coroutine_yield("CALL", session))
 end
 
 function skynet.rawcall(addr, typename, msg, sz)
 	local p = proto[typename]
 	local session = c.send(addr, p.id , nil , msg, sz)
-	return coroutine_yield("CALL", session)
+	return coroutine_yield("CALL", assert(session, "call to invalid address"))
 end
 
 function skynet.ret(msg, sz)
@@ -405,7 +409,7 @@ do
 			f = function(...)
 				local addr = remote_query(t.__remote)
 				-- the proto is 11 (lua is 10)
-				local session = _send(addr, 11 , nil, _pack(t,method,...))
+				local session = assert(_send(addr, 11 , nil, _pack(t,method,...)), "call to invalid address")
 				local msg, sz = _yield("CALL", session)
 				return select(2,assert(_unpack(msg,sz)))
 			end
diff --git a/skynet-src/skynet_mq.c b/skynet-src/skynet_mq.c
index ffd6c45c..abdeb9b0 100644
--- a/skynet-src/skynet_mq.c
+++ b/skynet-src/skynet_mq.c
@@ -147,6 +147,19 @@ expand_queue(struct message_queue *q) {
 	q->queue = new_queue;
 }
 
+static void
+_unlock(struct message_queue *q) {
+	// this api use in push a unlock message, so the in_global flags must not be 0 , 
+	// but the q is not exist in global queue.
+	if (q->in_global == MQ_LOCKED) {
+		skynet_globalmq_push(q);
+		q->in_global = MQ_IN_GLOBAL;
+	} else {
+		assert(q->in_global == MQ_DISPATCHING);
+	}
+	q->lock_session = 0;
+}
+
 static void 
 _pushhead(struct message_queue *q, struct skynet_message *message) {
 	int head = q->head - 1;
@@ -162,15 +175,7 @@ _pushhead(struct message_queue *q, struct skynet_message *message) {
 	q->queue[head] = *message;
 	q->head = head;
 
-	// this api use in push a unlock message, so the in_global flags must not be 0 , 
-	// but the q is not exist in global queue.
-	if (q->in_global == MQ_LOCKED) {
-		skynet_globalmq_push(q);
-		q->in_global = MQ_IN_GLOBAL;
-	} else {
-		assert(q->in_global == MQ_DISPATCHING);
-	}
-	q->lock_session = 0;
+	_unlock(q);
 }
 
 void 
@@ -211,6 +216,13 @@ skynet_mq_lock(struct message_queue *q, int session) {
 	UNLOCK(q)
 }
 
+void
+skynet_mq_unlock(struct message_queue *q) {
+	LOCK(q)
+	_unlock(q);
+	UNLOCK(q)
+}
+
 void 
 skynet_mq_init() {
 	struct global_queue *q = malloc(sizeof(*q));
diff --git a/skynet-src/skynet_mq.h b/skynet-src/skynet_mq.h
index bd71e91f..ced1beff 100644
--- a/skynet-src/skynet_mq.h
+++ b/skynet-src/skynet_mq.h
@@ -24,6 +24,7 @@ uint32_t skynet_mq_handle(struct message_queue *);
 int skynet_mq_pop(struct message_queue *q, struct skynet_message *message);
 void skynet_mq_push(struct message_queue *q, struct skynet_message *message);
 void skynet_mq_lock(struct message_queue *q, int session);
+void skynet_mq_unlock(struct message_queue *q);
 
 void skynet_mq_force_push(struct message_queue *q);
 void skynet_mq_pushglobal(struct message_queue *q);
diff --git a/skynet-src/skynet_server.c b/skynet-src/skynet_server.c
index dda09622..05c83618 100644
--- a/skynet-src/skynet_server.c
+++ b/skynet-src/skynet_server.c
@@ -384,6 +384,14 @@ skynet_command(struct skynet_context * context, const char * cmd , const char *
 		return NULL;
 	}
 
+	if (strcmp(cmd,"UNLOCK") == 0) {
+		if (context->init == false) {
+			return NULL;
+		}
+		skynet_mq_unlock(context->queue);
+		return NULL;
+	}
+
 	if (strcmp(cmd,"REG") == 0) {
 		if (param == NULL || param[0] == '\0') {
 			sprintf(context->result, ":%x", context->handle);