(Merge 3.3) Issue #20311: select.epoll.poll() now rounds the timeout away from

zero, instead of rounding towards zero. For example, a timeout of one
microsecond is now rounded to one millisecond, instead of being rounded to
zero.

Lib/test/test_epoll.py

@@ -47,6 +47,17 @@ class TestEPoll(unittest.TestCase):
         self.serverSocket.listen(1)
         self.connections = [self.serverSocket]
 
+    def test_timeout_rounding(self):
+        # epoll_wait() has a resolution of 1 millisecond, check if the timeout
+        # is correctly rounded to the upper bound
+        epoll = select.epoll()
+        self.addCleanup(epoll.close)
+        for timeout in (1e-2, 1e-3, 1e-4):
+            t0 = time.perf_counter()
+            epoll.poll(timeout)
+            dt = time.perf_counter() - t0
+            self.assertGreaterEqual(dt, timeout)
+
 
     def tearDown(self):
         for skt in self.connections: