allows loop pause for subseconds (#50461)

* allows loop pause for subseconds
* skip test on os x and bsd since date commands lacks nano

fixes #49951

changelogs/fragments/pause_subsecs.yml

@@ -0,0 +1,2 @@
+minor_changes:
+    - loop_control's pause now allows for fractions of a second

lib/ansible/playbook/loop_control.py

@@ -28,7 +28,7 @@ class LoopControl(FieldAttributeBase):
     _loop_var = FieldAttribute(isa='str', default='item')
     _index_var = FieldAttribute(isa='str')
     _label = FieldAttribute(isa='str')
-    _pause = FieldAttribute(isa='int', default=0)
+    _pause = FieldAttribute(isa='float', default=0)
     _extended = FieldAttribute(isa='bool')
 
     def __init__(self):

test/integration/targets/loops/tasks/main.yml

@@ -23,6 +23,25 @@
     that:
     - '(after.stdout |int) - (before.stdout|int) >= 4'
 
+- name: test subsecond pause
+  block:
+    - name: Measure time before loop with .5s pause
+      set_fact:
+        times: "{{times|default([]) + [ lookup('pipe','date +%s.%3N') ]}}"
+      with_sequence: count=3
+      loop_control:
+        pause: 0.6
+
+    - name: ensure lag, since there is 3 rounds, and 0.5 seconds between, it should last 1.2 seconds, but allowing leeway due to CI lag
+      assert:
+        that:
+            - tdiff|float >= 1.2
+            - tdiff|int < 3
+      vars:
+        tdiff: '{{ times[2]|float - times[0]|float }}'
+  when:
+    - ansible_facts['distribution'] not in ("MacOSX", "FreeBSD")
+
 #
 # Tests of loop syntax with args
 #