fix semaphore aquire bug

Author: carolFrohlich

nipype/pipeline/plugins/multiproc.py

@@ -160,7 +160,6 @@ def __init__(self, plugin_args=None):
     def _wait(self):
         if len(self.pending_tasks) > 0:
             semaphore_singleton.semaphore.acquire()
-        semaphore_singleton.semaphore.release()
 
     def _get_result(self, taskid):
         if taskid not in self._taskresult:

nipype/pipeline/plugins/semaphore_singleton.py

@@ -1,4 +1,4 @@
 # -*- coding: utf-8 -*-
 from __future__ import print_function, division, unicode_literals, absolute_import
 import threading
-semaphore = threading.Semaphore(1)
+semaphore = threading.Semaphore(0)