subprocess iostreams only send on flush

IPython/kernel/zmq/iostream.py

@@ -41,7 +41,7 b' class OutStream(object):'
         self.name = name
         self.parent_header = {}
         self._new_buffer()
-        self._found_newprocess = threading.Event()
+        self._found_newprocess = 0
         self._buffer_lock = threading.Lock()
         self._master_pid = os.getpid()
         self._master_thread = threading.current_thread().ident
@@ -50,21 +50,16 b' class OutStream(object):'
     
     def _setup_pipe_in(self):
         """setup listening pipe for subprocesses"""
-        ctx = self._pipe_ctx = zmq.Context()
-        
-        # signal pair for terminating background thread
-        self._pipe_signaler = ctx.socket(zmq.PAIR)
-        self._pipe_signalee = ctx.socket(zmq.PAIR)
-        self._pipe_signaler.bind("inproc://ostream_pipe")
-        self._pipe_signalee.connect("inproc://ostream_pipe")
-        # thread event to signal cleanup is done
-        self._pipe_done = threading.Event() 
+        ctx = self.pub_socket.context
         
         # use UUID to authenticate pipe messages
         self._pipe_uuid = uuid.uuid4().bytes
         
-        self._pipe_thread = threading.Thread(target=self._pipe_main)
-        self._pipe_thread.start()
+        self._pipe_in = ctx.socket(zmq.PULL)
+        self._pipe_in.linger = 0
+        self._pipe_port = self._pipe_in.bind_to_random_port("tcp://127.0.0.1")
+        self._pipe_poller = zmq.Poller()
+        self._pipe_poller.register(self._pipe_in, zmq.POLLIN)
     
     def _setup_pipe_out(self):
         # must be new context after fork
@@ -74,51 +69,6 b' class OutStream(object):'
         self._pipe_out_lock = threading.Lock()
         self._pipe_out.connect("tcp://127.0.0.1:%i" % self._pipe_port)
     
-    def _pipe_main(self):
-        """eventloop for receiving"""
-        ctx = self._pipe_ctx
-        self._pipe_in = ctx.socket(zmq.PULL)
-        self._pipe_port = self._pipe_in.bind_to_random_port("tcp://127.0.0.1")
-        poller = zmq.Poller()
-        poller.register(self._pipe_signalee, zmq.POLLIN)
-        poller.register(self._pipe_in, zmq.POLLIN)
-        while True:
-            if not self._is_master_process():
-                return
-            try:
-                events = dict(poller.poll(1000))
-            except zmq.ZMQError:
-                # should only be triggered by process-ending cleanup
-                return
-            
-            if self._pipe_signalee in events:
-                break
-            if self._pipe_in in events:
-                msg = self._pipe_in.recv_multipart()
-                if msg[0] != self._pipe_uuid:
-                    # message not authenticated
-                    continue
-                self._found_newprocess.set()
-                text = msg[1].decode(self.encoding, 'replace')
-                with self._buffer_lock:
-                    self._buffer.write(text)
-                    if self._start < 0:
-                        self._start = time.time()
-        
-        # wrap it up
-        self._pipe_signaler.close()
-        self._pipe_signalee.close()
-        self._pipe_in.close()
-        self._pipe_ctx.term()
-        self._pipe_done.set()
-    
-    
-    def __del__(self):
-        if not self._is_master_process():
-            return
-        self._pipe_signaler.send(b'die')
-        self._pipe_done.wait(10)
-    
     def _is_master_process(self):
         return os.getpid() == self._master_pid
     
@@ -131,7 +81,7 b' class OutStream(object):'
     def _check_mp_mode(self):
         """check for forks, and switch to zmq pipeline if necessary"""
         if self._is_master_process():
-            if self._found_newprocess.is_set():
+            if self._found_newprocess:
                 return MASTER_WITH_CHILDREN
             else:
                 return MASTER_NO_CHILDREN
@@ -147,42 +97,57 b' class OutStream(object):'
     def close(self):
         self.pub_socket = None
 
+    def _flush_from_subprocesses(self):
+        """flush possible pub data from subprocesses into my buffer"""
+        if not self._is_master_process():
+            return
+        for i in range(100):
+            if self._pipe_poller.poll(0):
+                msg = self._pipe_in.recv_multipart()
+                if msg[0] != self._pipe_uuid:
+                    continue
+                else:
+                    self._buffer.write(msg[1].decode(self.encoding, 'replace'))
+                    # this always means a flush,
+                    # so reset our timer
+                    self._start = 0
+            else:
+                break
+    
     def flush(self):
         """trigger actual zmq send"""
         if self.pub_socket is None:
             raise ValueError(u'I/O operation on closed file')
+        
+        mp_mode = self._check_mp_mode()
+        
+        if mp_mode != CHILD:
+            # we are master
+            if not self._is_master_thread():
+                # sub-threads must not trigger flush,
+                # but at least they can force the timer.
+                self._start = 0
+                return
+            
+            self._flush_from_subprocesses()
+            data = self._flush_buffer()
+            
+            if data:
+                content = {u'name':self.name, u'data':data}
+                msg = self.session.send(self.pub_socket, u'stream', content=content,
+                                       parent=self.parent_header, ident=self.topic)
+            
+                if hasattr(self.pub_socket, 'flush'):
+                    # socket itself has flush (presumably ZMQStream)
+                    self.pub_socket.flush()
         else:
-            if self._is_master_process():
-                if not self._is_master_thread():
-                    # sub-threads mustn't trigger flush,
-                    # but at least they can force the timer.
-                    self._start = 0
-                data = u''
-                # obtain data
-                if self._check_mp_mode(): # multiprocess, needs a lock
-                    with self._buffer_lock:
-                        data = self._buffer.getvalue()
-                        self._buffer.close()
-                        self._new_buffer()
-                else: # single process mode
-                    data = self._buffer.getvalue()
-                    self._buffer.close()
-                    self._new_buffer()
-
-                if data:
-                    content = {u'name':self.name, u'data':data}
-                    msg = self.session.send(self.pub_socket, u'stream', content=content,
-                                           parent=self.parent_header, ident=self.topic)
-
-                    if hasattr(self.pub_socket, 'flush'):
-                        # socket itself has flush (presumably ZMQStream)
-                        self.pub_socket.flush()
-            else:
-                self._check_mp_mode()
-                with self._pipe_out_lock:
-                    tracker = self._pipe_out.send(b'', copy=False, track=True)
-                    tracker.wait(1)
-
+            with self._pipe_out_lock:
+                string = self._flush_buffer()
+                tracker = self._pipe_out.send_multipart([
+                    self._pipe_uuid,
+                    string.encode(self.encoding, 'replace'),
+                ], copy=False, track=True)
+                tracker.wait(1)
 
     def isatty(self):
         return False
@@ -206,21 +171,10 b' class OutStream(object):'
             # Make sure that we're handling unicode
             if not isinstance(string, unicode):
                 string = string.decode(self.encoding, 'replace')
-            
-            mp_mode = self._check_mp_mode()
-            if mp_mode == CHILD:
-                with self._pipe_out_lock:
-                    self._pipe_out.send_multipart([
-                        self._pipe_uuid,
-                        string.encode(self.encoding, 'replace'),
-                    ])
-                return
-            elif mp_mode == MASTER_NO_CHILDREN:
-                self._buffer.write(string)
-            elif mp_mode == MASTER_WITH_CHILDREN:
-                with self._buffer_lock:
-                    self._buffer.write(string)
-
+            self._buffer.write(string)
+            self._check_mp_mode()
+            # do we want to check subprocess flushes on write?
+            # self._flush_from_subprocesses()
             current_time = time.time()
             if self._start < 0:
                 self._start = current_time
@@ -234,6 +188,16 b' class OutStream(object):'
             for string in sequence:
                 self.write(string)
 
+    def _flush_buffer(self):
+        """clear the current buffer and return the current buffer data"""
+        data = u''
+        if self._buffer is not None:
+            data = self._buffer.getvalue()
+            self._buffer.close()
+        self._new_buffer()
+        return data
+    
     def _new_buffer(self):
         self._buffer = StringIO()
         self._start = -1
+        

IPython/zmq/tests/test_kernel.py

@@ -151,7 +151,7 b' def test_subprocess_print():'
         for n in range(np):
             nt.assert_equal(stdout.count(str(n)), 1, stdout)
         nt.assert_equal(stderr, '')
-        _check_mp_mode(km, expected=True)
+        _check_mp_mode(km, expected=False)
         _check_mp_mode(km, expected=False, stream="stderr")
 
 
@@ -199,5 +199,5 b' def test_subprocess_error():'
         nt.assert_true("ZeroDivisionError" in stderr, stderr)
 
         _check_mp_mode(km, expected=False)
-        _check_mp_mode(km, expected=True, stream="stderr")
+        _check_mp_mode(km, expected=False, stream="stderr")