diff --git a/timmy/nodes.py b/timmy/nodes.py
index 57eb643..767c14d 100644
--- a/timmy/nodes.py
+++ b/timmy/nodes.py
@@ -501,8 +501,10 @@ class Nodes(object):
                                                      'odir': odir,
                                                      'fake': fake},
                                                key=key))
-        self.nodes = tools.run_batch(run_items, 100, dict_result=True)
-        lock.unlock()
+        try:
+            self.nodes = tools.run_batch(run_items, 100, dict_result=True)
+        finally:
+            lock.unlock()
 
     def calculate_log_size(self, timeout=15):
         total_size = 0
diff --git a/timmy/tools.py b/timmy/tools.py
index d848717..33e773b 100644
--- a/timmy/tools.py
+++ b/timmy/tools.py
@@ -67,7 +67,9 @@ class SemaphoreProcess(Process):
 
     def run(self):
         try:
-            self.queue.put_nowait(self.target(**self.args))
+            result = self.target(**self.args)
+            if self.queue:
+                self.queue.put_nowait(result)
         finally:
             logging.debug('finished call: %s' % self.target)
             self.semaphore.release()