diff --git a/asio b/asio
index 77ed33821d6473d6904ef3171e318181c015003a..0355fc59807198034780c814c799ed353ffe960f 160000
--- a/asio
+++ b/asio
@@ -1 +1 @@
-Subproject commit 77ed33821d6473d6904ef3171e318181c015003a
+Subproject commit 0355fc59807198034780c814c799ed353ffe960f
diff --git a/examples/file_server/file_socket.cpp b/examples/file_server/file_socket.cpp
index fa440d92fbad451bf1bd92b95d4c21316b0c1b07..8f9e148a0b86c9496207161e9193950fe5c0772e 100644
--- a/examples/file_server/file_socket.cpp
+++ b/examples/file_server/file_socket.cpp
@@ -57,7 +57,7 @@ void file_socket::handle_msg(out_msg_ctype& msg)
 	switch (*msg.data())
 	{
 	case 0:
-		if (TRANS_IDLE == state)
+		if (TRANS_IDLE == state && !is_sending()) //avoid accessing the send queue concurrently, because we used non_lock_queue
 		{
 			trans_end();