[Python-checkins] cpython (merge 3.5 -> default): Merge 3.5 (issue #27456)

[yury.selivanov]

https://hg.python.org/cpython/rev/10384c5c18f5
changeset:   103675:10384c5c18f5
parent:      103673:681096fb4aac
parent:      103674:3f7e4ae9eba3
user:        Yury Selivanov <yury at magic.io>
date:        Sun Sep 11 21:44:17 2016 -0400
summary:
  Merge 3.5 (issue #27456)

files:
  Lib/asyncio/selector_events.py |  16 ++++++++++++++++
  Misc/NEWS                      |   2 ++
  2 files changed, 18 insertions(+), 0 deletions(-)


diff --git a/Lib/asyncio/selector_events.py b/Lib/asyncio/selector_events.py
--- a/Lib/asyncio/selector_events.py
+++ b/Lib/asyncio/selector_events.py
@@ -39,6 +39,17 @@
         return bool(key.events & event)
 
 
+if hasattr(socket, 'TCP_NODELAY'):
+    def _set_nodelay(sock):
+        if (sock.family in {socket.AF_INET, socket.AF_INET6} and
+                sock.type == socket.SOCK_STREAM and
+                sock.proto == socket.IPPROTO_TCP):
+            sock.setsockopt(socket.IPPROTO_TCP, socket.TCP_NODELAY, 1)
+else:
+    def _set_nodelay(sock):
+        pass
+
+
 class BaseSelectorEventLoop(base_events.BaseEventLoop):
     """Selector event loop.
 
@@ -641,6 +652,11 @@
         self._eof = False
         self._paused = False
 
+        # Disable the Nagle algorithm -- small writes will be
+        # sent without waiting for the TCP ACK.  This generally
+        # decreases the latency (in some cases significantly.)
+        _set_nodelay(self._sock)
+
         self._loop.call_soon(self._protocol.connection_made, self)
         # only start reading when connection_made() has been called
         self._loop.call_soon(self._loop.add_reader,
diff --git a/Misc/NEWS b/Misc/NEWS
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -365,6 +365,8 @@
 
 - asyncio: Add set_protocol / get_protocol to Transports.
 
+- Issue #27456: asyncio: Set TCP_NODELAY by default.
+
 IDLE
 ----
 

-- 
Repository URL: https://hg.python.org/cpython