From f8b6c774ddd81e8f3cb1fd18b1a7211aaaf0f031 Mon Sep 17 00:00:00 2001
From: David Wilson <dw@botanicus.net>
Date: Tue, 11 Sep 2018 18:22:58 +0100
Subject: [PATCH] issue #362: cap max open files in children.

---
 ansible_mitogen/target.py | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/ansible_mitogen/target.py b/ansible_mitogen/target.py
index ae7990a9..347dc3c2 100644
--- a/ansible_mitogen/target.py
+++ b/ansible_mitogen/target.py
@@ -43,6 +43,7 @@ import operator
 import os
 import pwd
 import re
+import resource
 import signal
 import stat
 import subprocess
@@ -90,6 +91,15 @@ _fork_parent = None
 good_temp_dir = None
 
 
+# subprocess.Popen(close_fds=True) aka. AnsibleModule.run_command() loops the
+# entire SC_OPEN_MAX space. CentOS>5 ships with 1,048,576 FDs by default,
+# resulting in huge (>500ms) runtime waste running many commands. Therefore if
+# we are a child context, cap the insane FD count to something reasonable.
+if subprocess.MAXFD > 512 and not mitogen.is_master:
+    subprocess.MAXFD = 512
+    resource.setrlimit(resource.RLIMIT_NOFILE, (512, 512))
+
+
 def get_small_file(context, path):
     """
     Basic in-memory caching module fetcher. This generates an one roundtrip for