Made pool with no daemon

pypushflow/PythonActor.py

@@ -31,6 +31,7 @@ import traceback
 import functools
 import importlib
 import multiprocessing
+import multiprocessing.pool
 
 from pypushflow.AbstractActor import AbstractActor
 
@@ -65,12 +66,37 @@ def trace_unhandled_exceptions(func):
     return wrapped_func
 
 
+#############################################################################
+# Create no daemon processes
+# See : https://stackoverflow.com/a/8963618
+#
+
+class NoDaemonProcess(multiprocessing.Process):
+    # make 'daemon' attribute always return False
+    def _get_daemon(self):
+        return False
+
+    def _set_daemon(self, value):
+        pass
+    daemon = property(_get_daemon, _set_daemon)
+
+# We sub-class multiprocessing.pool.Pool instead of multiprocessing.Pool
+# because the latter is only a wrapper function, not a proper class.
+
+
+class Edna2Pool(multiprocessing.pool.Pool):
+    Process = NoDaemonProcess
+
+#
+#
+#############################################################################
+
 class AsyncFactory:
     def __init__(self, func, callback=None, errorCallback=None):
         self.func = func
         self.callback = callback
         self.errorCallback = errorCallback
-        self.pool = multiprocessing.Pool()
+        self.pool = Edna2Pool()
 
     def call(self, *args, **kwargs):
         logger.debug('Before apply_async, func={0}, callback={1}, errorCallback={2}'.format(