Sleep briefly while waiting for pending results to reduce CPU churn

lib/ansible/plugins/strategy/__init__.py

@@ -71,14 +71,12 @@ class SharedPluginLoaderObj:
 
 _sentinel = object()
 def results_thread_main(strategy):
-    #print("RESULT THREAD STARTING: %s" % threading.current_thread())
     while True:
         try:
             result = strategy._final_q.get()
             if type(result) == object:
                 break
             else:
-                #print("result in thread is: %s" % result._result)
                 strategy._results_lock.acquire()
                 strategy._results.append(result)
                 strategy._results_lock.release()
@@ -86,7 +84,6 @@ def results_thread_main(strategy):
             break
         except Queue.Empty:
             pass
-    #print("RESULT THREAD EXITED: %s" % threading.current_thread())
 
 class StrategyBase:
 
@@ -121,7 +118,7 @@ class StrategyBase:
         self._results = deque()
         self._results_lock = threading.Condition(threading.Lock())
 
-        #print("creating thread for strategy %s" % id(self))
+        # create the result processing thread for reading results in the background
         self._results_thread = threading.Thread(target=results_thread_main, args=(self,))
         self._results_thread.daemon = True
         self._results_thread.start()
@@ -316,7 +313,6 @@ class StrategyBase:
                 continue
 
             if original_task.register:
-                #print("^ REGISTERING RESULT %s" % original_task.register)
                 if original_task.run_once:
                     host_list = [host for host in self._inventory.get_hosts(iterator._play.hosts) if host.name not in self._tqm._unreachable_hosts]
                 else:
@@ -533,6 +529,8 @@ class StrategyBase:
 
             results = self._process_pending_results(iterator)
             ret_results.extend(results)
+            if self._pending_results > 0:
+                time.sleep(0.001)
 
         display.debug("no more pending results, returning what we have")