diff --git a/xlib/mt/MTOrderedData.py b/xlib/mt/MTOrderedData.py
new file mode 100644
index 0000000..2b30709
--- /dev/null
+++ b/xlib/mt/MTOrderedData.py
@@ -0,0 +1,89 @@
+from collections import deque
+from queue import Queue
+from typing import Any, Union, Tuple
+
+def MTOrderedData(queue_size=0):
+    """
+    Multithreaded ordered work.
+    
+    Ensures the order of work done by threads.
+    returns (host,client)  classes.
+    """
+    h2c, c2h = Queue(maxsize=queue_size), Queue(maxsize=queue_size)
+    
+    host = _MTOrderedDataHost(h2c, c2h)
+    cli  = _MTOrderedDataClient(h2c, c2h)
+    return host, cli
+
+class _MTOrderedDataHost:
+    """
+    """
+    def __init__(self, h2c : Queue, c2h : Queue):
+        self._h2c = h2c
+        self._c2h = c2h
+        self._counter = 0
+        
+        self._sent_ids = deque()
+        self._done_datas = {}
+    
+    def send(self, data):
+        """
+        send the data to the clients
+        """
+        if data is None:
+            raise ValueError('data cannot be None')
+            
+        c = self._counter
+        self._counter += 1
+        self._sent_ids.append(c)
+        
+        self._h2c.put( (c, data) )
+        
+    def recv(self) -> Union[Any, None]:
+        sent_ids = self._sent_ids
+        
+        if len(sent_ids) != 0:
+            done_datas = self._done_datas
+            
+            while not self._c2h.empty():
+                id, data = self._c2h.get()
+                done_datas[id] = data
+            
+            id = sent_ids[0]
+
+            if id in done_datas:
+                done_data = done_datas.pop(id)
+                sent_ids.popleft()
+                print('len(sent_ids) ', len(sent_ids))
+                return done_data
+            
+        return None
+    
+    
+class _MTOrderedDataClient:
+    
+    
+    def __init__(self, h2c : Queue, c2h : Queue):
+        self._h2c = h2c
+        self._c2h = c2h
+    
+        
+    def send(self, data_id, data):
+        """
+        """
+        self._c2h.put( (data_id, data) )
+        
+        
+    def recv(self, wait=True) -> Tuple[int, Any]:
+        """
+        returns ( data_id(int), data(Any) ) or None
+        """
+        h2c = self._h2c
+        
+        if not wait and h2c.empty():
+            return None
+            
+        id, data = h2c.get()
+        return id, data
+        
+    
diff --git a/xlib/mt/__init__.py b/xlib/mt/__init__.py
new file mode 100644
index 0000000..8288013
--- /dev/null
+++ b/xlib/mt/__init__.py
@@ -0,0 +1,5 @@
+"""
+various threading extensions
+"""
+
+from .MTOrderedData import MTOrderedData
\ No newline at end of file