Use ceil(timeout) to avoid truncation

Author: giampaolo

Lib/subprocess.py

@@ -51,7 +51,6 @@
 import threading
 import warnings
 import contextlib
-import functools
 import math
 from time import monotonic as _time
 import types
@@ -2079,7 +2078,7 @@ def _wait_pidfd(self, timeout):
             try:
                 poller = select.poll()
                 poller.register(pidfd, select.POLLIN)
-                events = poller.poll(int(timeout * 1000))
+                events = poller.poll(math.ceil(timeout * 1000))
                 if not events:
                     raise TimeoutExpired(self.args, timeout)
                 return True