gh-101336: Add keep_alive keyword arg for asyncio create_server() (#112485)

Author: beavailable

Doc/library/asyncio-eventloop.rst

@@ -671,6 +671,7 @@ Creating network servers
                         flags=socket.AI_PASSIVE, \
                         sock=None, backlog=100, ssl=None, \
                         reuse_address=None, reuse_port=None, \
+                        keep_alive=None, \
                         ssl_handshake_timeout=None, \
                         ssl_shutdown_timeout=None, \
                         start_serving=True)
@@ -735,6 +736,13 @@ Creating network servers
      set this flag when being created. This option is not supported on
      Windows.
 
+   * *keep_alive* set to ``True`` keeps connections active by enabling the
+     periodic transmission of messages.
+
+   .. versionchanged:: 3.13
+
+      Added the *keep_alive* parameter.
+
    * *ssl_handshake_timeout* is (for a TLS server) the time in seconds to wait
      for the TLS handshake to complete before aborting the connection.
      ``60.0`` seconds if ``None`` (default).

Lib/asyncio/base_events.py

@@ -1496,6 +1496,7 @@ async def create_server(
             ssl=None,
             reuse_address=None,
             reuse_port=None,
+            keep_alive=None,
             ssl_handshake_timeout=None,
             ssl_shutdown_timeout=None,
             start_serving=True):
@@ -1569,6 +1570,9 @@ async def create_server(
                             socket.SOL_SOCKET, socket.SO_REUSEADDR, True)
                     if reuse_port:
                         _set_reuseport(sock)
+                    if keep_alive:
+                        sock.setsockopt(
+                            socket.SOL_SOCKET, socket.SO_KEEPALIVE, True)
                     # Disable IPv4/IPv6 dual stack support (enabled by
                     # default on Linux) which makes a single socket
                     # listen on both address families.

Lib/asyncio/events.py

@@ -316,6 +316,7 @@ async def create_server(
             *, family=socket.AF_UNSPEC,
             flags=socket.AI_PASSIVE, sock=None, backlog=100,
             ssl=None, reuse_address=None, reuse_port=None,
+            keep_alive=None,
             ssl_handshake_timeout=None,
             ssl_shutdown_timeout=None,
             start_serving=True):
@@ -354,6 +355,9 @@ async def create_server(
         they all set this flag when being created. This option is not
         supported on Windows.
 
+        keep_alive set to True keeps connections active by enabling the
+        periodic transmission of messages.
+
         ssl_handshake_timeout is the time in seconds that an SSL server
         will wait for completion of the SSL handshake before aborting the
         connection. Default is 60s.

Misc/NEWS.d/next/Library/2023-11-28-02-39-30.gh-issue-101336.ya433z.rst

@@ -0,0 +1 @@
+Add ``keep_alive`` keyword parameter for :meth:`AbstractEventLoop.create_server` and :meth:`BaseEventLoop.create_server`.