issue5738: The distribution example was confusing, and out of date. It's too…

issue5738: The distribution example was confusing, and out of date. It's too large to include inline in the docs as well. It belongs in an addons module outside the stdlib. Removing.

Doc/library/multiprocessing.rst

@@ -2230,10 +2230,3 @@ Some simple benchmarks comparing :mod:`multiprocessing` with :mod:`threading`:
 
 .. literalinclude:: ../includes/mp_benchmarks.py
 
-An example/demo of how to use the :class:`managers.SyncManager`, :class:`Process`
-and others to build a system which can distribute processes and work via a
-distributed queue to a "cluster" of machines on a network, accessible via SSH.
-You will need to have private key authentication for all hosts configured for
-this to work.
-
-.. literalinclude:: ../includes/mp_distributing.py

Lib/multiprocessing/queues.py

@@ -47,6 +47,8 @@ class Queue(object):
         if sys.platform != 'win32':
             register_after_fork(self, Queue._after_fork)
 
+        self.getv = 0
+
     def __getstate__(self):
         assert_spawning(self)
         return (self._maxsize, self._reader, self._writer,
@@ -71,6 +73,8 @@ class Queue(object):
         self._poll = self._reader.poll
 
     def put(self, obj, block=True, timeout=None):
+        if not isinstance(obj, list):
+            debug('put: %s', obj)
         assert not self._closed
         if not self._sem.acquire(block, timeout):
             raise Full
@@ -85,11 +89,15 @@ class Queue(object):
             self._notempty.release()
 
     def get(self, block=True, timeout=None):
+        self.getv += 1
+        debug('self.getv: %s', self.getv)
         if block and timeout is None:
             self._rlock.acquire()
             try:
                 res = self._recv()
                 self._sem.release()
+                if not isinstance(res, list):
+                    debug('get: %s', res)
                 return res
             finally:
                 self._rlock.release()
@@ -104,6 +112,8 @@ class Queue(object):
                     raise Empty
                 res = self._recv()
                 self._sem.release()
+                if not isinstance(res, list):
+                    debug('get: %s', res)
                 return res
             finally:
                 self._rlock.release()
@@ -229,16 +239,22 @@ class Queue(object):
                 try:
                     while 1:
                         obj = bpopleft()
+                        if not isinstance(obj, list):
+                            debug('feeder thread got: %s', obj)
                         if obj is sentinel:
                             debug('feeder thread got sentinel -- exiting')
                             close()
                             return
-
                         if wacquire is None:
+                            if not isinstance(obj, list):
+                                debug('sending to pipe: %s', obj)
                             send(obj)
                         else:
-                            wacquire()
+                            debug('waiting on wacquire')
+                            wacquire(timeout=30)
                             try:
+                                if not isinstance(obj, list):
+                                    debug('sending to pipe: %s', obj)
                                 send(obj)
                             finally:
                                 wrelease()