Removed Sized and MacSafeQueues (#3945)

These are both unused (since PR #3944)

See issue #3929 for more discussion

# Changed Behaviour

This is removing now-unused code

# Fixes

Fixes #3929

## Type of change

- Code maintenance/cleanup

Author: benclifford

parsl/multiprocessing.py

@@ -4,7 +4,6 @@
 import logging
 import multiprocessing
 import multiprocessing.queues
-import platform
 from multiprocessing.context import ForkProcess as ForkProcessType
 from multiprocessing.context import SpawnProcess as SpawnProcessType
 from typing import Callable
@@ -21,54 +20,6 @@
 SpawnQueue = SpawnContext.Queue
 
 
-class MacSafeQueue(multiprocessing.queues.Queue):
-    """ Multiprocessing queues do not have qsize attributes on MacOS.
-    This is slower but more portable version of the multiprocessing Queue
-    that adds a explicit counter
-
-    Reference : https://github.com/keras-team/autokeras/commit/4ddd568b06b4045ace777bc0fb7bc18573b85a75
-    """
-
-    def __init__(self, *args, **kwargs):
-        if 'ctx' not in kwargs:
-            kwargs['ctx'] = multiprocessing.get_context('spawn')
-        super().__init__(*args, **kwargs)
-        self._counter = multiprocessing.Value('i', 0)
-
-    def put(self, *args, **kwargs):
-        # logger.critical("Putting item {}".format(args))
-        x = super().put(*args, **kwargs)
-        with self._counter.get_lock():
-            self._counter.value += 1
-        return x
-
-    def get(self, *args, **kwargs):
-        x = super().get(*args, **kwargs)
-        with self._counter.get_lock():
-            self._counter.value -= 1
-        # logger.critical("Getting item {}".format(x))
-        return x
-
-    def qsize(self):
-        return self._counter.value
-
-    def empty(self):
-        return not self._counter.value
-
-
-# SizedQueue should be constructable using the same calling
-# convention as multiprocessing.Queue but that entire signature
-# isn't expressible in mypy 0.790
-SizedQueue: Callable[..., multiprocessing.Queue]
-
-
-if platform.system() != 'Darwin':
-    import multiprocessing
-    SizedQueue = SpawnQueue
-else:
-    SizedQueue = MacSafeQueue
-
-
 def join_terminate_close_proc(process: SpawnProcessType, *, timeout: int = 30) -> None:
     """Increasingly aggressively terminate a process.