From 27f2051c44a3dd614b391e3f5ae7dca97257f64b Mon Sep 17 00:00:00 2001
From: Justus Winter <4winter@informatik.uni-hamburg.de>
Date: Tue, 22 Jan 2013 18:31:57 +0100
Subject: Join worker processes and keep track of them in the log

This also prevents a zombie from hanging around until the next worker
is spawned by multiprocessing.

Fixes 411.

Signed-off-by: Justus Winter <4winter@informatik.uni-hamburg.de>
---
 alot/db/manager.py | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/alot/db/manager.py b/alot/db/manager.py
index 535186b5..bf1581ff 100644
--- a/alot/db/manager.py
+++ b/alot/db/manager.py
@@ -8,6 +8,7 @@ import logging
 import sys
 import errno
 import signal
+from twisted.internet import reactor
 
 from collections import deque
 
@@ -312,6 +313,23 @@ class DBManager(object):
         process = FillPipeProcess(cbl(), pipe, fun)
         process.start()
         self.processes.append(process)
+        logging.debug('Worker process {0} spawned'.format(process.pid))
+
+        def threaded_wait():
+            process.join()
+
+            if process.exitcode < 0:
+                msg = 'received signal {0}'.format(-process.exitcode)
+            elif process.exitcode > 0:
+                msg = 'returned error code {0}'.format(process.exitcode)
+            else:
+                msg = 'exited successfully'
+
+            logging.debug('Worker process {0} {1}'.format(process.pid, msg))
+            self.processes.remove(process)
+
+        reactor.callInThread(threaded_wait)
+
         # closing the sending end in this (receiving) process guarantees
         # that here the apropriate EOFError is raised upon .recv in the walker
         sender.close()
-- 
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