[3.7] bpo-34263 Cap timeout submitted to epoll/select etc. to one day. (GH-8532)...

diff --git a/Lib/asyncio/base_events.py b/Lib/asyncio/base_events.py
index dc0ca3f02b9bf6323cf746cb0f2710cab3354556..a79e123e5113d9fc5410127ddb0514ae2472cfe9 100644 (file)
--- a/Lib/asyncio/base_events.py
+++ b/Lib/asyncio/base_events.py
@@ -63,6 +63,9 @@ _FATAL_ERROR_IGNORE = (BrokenPipeError,
 
 _HAS_IPv6 = hasattr(socket, 'AF_INET6')
 
+# Maximum timeout passed to select to avoid OS limitations
+MAXIMUM_SELECT_TIMEOUT = 24 * 3600
+
 
 def _format_handle(handle):
     cb = handle._callback
@@ -1702,7 +1705,7 @@ class BaseEventLoop(events.AbstractEventLoop):
         elif self._scheduled:
             # Compute the desired timeout.
             when = self._scheduled[0]._when
-            timeout = max(0, when - self.time())
+            timeout = min(max(0, when - self.time()), MAXIMUM_SELECT_TIMEOUT)
 
         if self._debug and timeout != 0:
             t0 = self.time()

diff --git a/Misc/NEWS.d/next/Library/2018-07-28-17-00-36.bpo-34263.zUfRsu.rst b/Misc/NEWS.d/next/Library/2018-07-28-17-00-36.bpo-34263.zUfRsu.rst
new file mode 100644 (file)
index 0000000..799463b
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2018-07-28-17-00-36.bpo-34263.zUfRsu.rst
@@ -0,0 +1,2 @@
+asyncio's event loop will not pass timeouts longer than one day to
+epoll/select etc.