ansible_mitogen: Fix "filedescriptor out of range in select()" in WorkerProcess

`mitogen.parent.POLLER_LIGHTWEIGHT` will normally be `PollPoller`, falling
back to `EpollPoller`, `KqueuePoller`, or `Poller`.

Fixes #957

Co-authored-by: Luca Berruti <nadirio@gmail.com>
Co-authored-by: Philippe Kueck <bqobccy6ejnq2bqvmebqiwqha4cs4@protected32.unixadm.org>

ansible_mitogen/process.py

@@ -281,11 +281,11 @@ def get_cpu_count(default=None):
 
 class Broker(mitogen.master.Broker):
     """
-    WorkerProcess maintains at most 2 file descriptors, therefore does not need
+    WorkerProcess maintains fewer file descriptors, therefore does not need
     the exuberant syscall expense of EpollPoller, so override it and restore
     the poll() poller.
     """
-    poller_class = mitogen.core.Poller
+    poller_class = mitogen.parent.POLLER_LIGHTWEIGHT
 
 
 class Binding(object):

docs/changelog.rst

@@ -22,6 +22,8 @@ Unreleased
 ----------
 
 * :gh:issue:`952` Fix Ansible `--ask-become-pass`, add test coverage
+* :gh:issue:`957` Fix Ansible exception when executing against 10s of hosts
+  "ValueError: filedescriptor out of range in select()"
 
 
 v0.3.7 (2024-04-08)

docs/contributors.rst

@@ -126,11 +126,13 @@ sponsorship and outstanding future-thinking of its early adopters.
     <li>jgadling</li>
     <li>John F Wall &mdash; <em>Making Ansible Great with Massive Parallelism</em></li>
     <li>KennethC</li>
+    <li><a href="https://github.com/lberruti">Luca Berruti</li>
     <li>Lewis Bellwood &mdash; <em>Happy to be apart of a great project.</em></li>
     <li>luto</li>
     <li><a href="https://mayeu.me/">Mayeu a.k.a Matthieu Maury</a></li>
     <li><a href="https://twitter.com/nathanhruby">@nathanhruby</a></li>
     <li><a href="https://github.com/opoplawski">Orion Poplawski</a></li>
+    <li><a href="https://github.com/philfry">Philippe Kueck</a></li>
     <li><a href="http://pageflows.com/">Ramy</a></li>
     <li>Scott Vokes</li>
     <li><a href="https://twitter.com/sirtux">Tom Eichhorn</a></li>