Issue #20311: EpollSelector now also rounds the timeout towards zero, as

PollSelector.

This change is not really required in Python 3.4, since select.epoll.poll() now
rounds also correctly the timeout. But Guido van Rossum prefers to have exactly
the same selectors.py file in CPython and Tulip projects: "it's not harmful".

1 files changed, 8 insertions, 1 deletions

diff --git a/Lib/selectors.py b/Lib/selectors.py
index f8b56cd433..1bdf972cdf 100644
--- a/Lib/selectors.py
+++ b/Lib/selectors.py
@@ -411,7 +411,14 @@ if hasattr(select, 'epoll'):
             return key
 
         def select(self, timeout=None):
-            timeout = -1 if timeout is None else max(timeout, 0)
+            if timeout is None:
+                timeout = -1
+            elif timeout <= 0:
+                timeout = 0
+            else:
+                # epoll_wait() has a resolution of 1 millisecond, round away
+                # from zero to wait *at least* timeout seconds.
+                timeout = math.ceil(timeout * 1e3) * 1e-3
             max_ev = len(self._fd_to_key)
             ready = []
             try: