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241 lines
8.6 KiB
Python
241 lines
8.6 KiB
Python
5 years ago
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###############################################################################
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# Queue and SimpleQueue implementation for loky
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#
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# authors: Thomas Moreau, Olivier Grisel
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#
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# based on multiprocessing/queues.py (16/02/2017)
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# * Add some compatibility function for python2.7 and 3.3 and makes sure
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# it uses the right synchronization primitive.
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# * Add some custom reducers for the Queues/SimpleQueue to tweak the
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# pickling process. (overload Queue._feed/SimpleQueue.put)
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#
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import os
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import sys
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import errno
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import weakref
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import threading
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from multiprocessing import util
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from multiprocessing import connection
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from multiprocessing.synchronize import SEM_VALUE_MAX
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from multiprocessing.queues import Full
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from multiprocessing.queues import _sentinel, Queue as mp_Queue
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from multiprocessing.queues import SimpleQueue as mp_SimpleQueue
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from .reduction import loads, dumps
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from .context import assert_spawning, get_context
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__all__ = ['Queue', 'SimpleQueue', 'Full']
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class Queue(mp_Queue):
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def __init__(self, maxsize=0, reducers=None, ctx=None):
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if sys.version_info[:2] >= (3, 4):
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super().__init__(maxsize=maxsize, ctx=ctx)
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else:
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if maxsize <= 0:
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# Can raise ImportError (see issues #3770 and #23400)
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maxsize = SEM_VALUE_MAX
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if ctx is None:
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ctx = get_context()
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self._maxsize = maxsize
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self._reader, self._writer = connection.Pipe(duplex=False)
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self._rlock = ctx.Lock()
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self._opid = os.getpid()
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if sys.platform == 'win32':
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self._wlock = None
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else:
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self._wlock = ctx.Lock()
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self._sem = ctx.BoundedSemaphore(maxsize)
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# For use by concurrent.futures
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self._ignore_epipe = False
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self._after_fork()
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if sys.platform != 'win32':
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util.register_after_fork(self, Queue._after_fork)
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self._reducers = reducers
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# Use custom queue set/get state to be able to reduce the custom reducers
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def __getstate__(self):
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assert_spawning(self)
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return (self._ignore_epipe, self._maxsize, self._reader, self._writer,
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self._reducers, self._rlock, self._wlock, self._sem,
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self._opid)
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def __setstate__(self, state):
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(self._ignore_epipe, self._maxsize, self._reader, self._writer,
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self._reducers, self._rlock, self._wlock, self._sem,
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self._opid) = state
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self._after_fork()
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# Overload _start_thread to correctly call our custom _feed
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def _start_thread(self):
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util.debug('Queue._start_thread()')
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# Start thread which transfers data from buffer to pipe
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self._buffer.clear()
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self._thread = threading.Thread(
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target=Queue._feed,
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args=(self._buffer, self._notempty, self._send_bytes,
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self._wlock, self._writer.close, self._reducers,
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self._ignore_epipe, self._on_queue_feeder_error, self._sem),
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name='QueueFeederThread'
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)
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self._thread.daemon = True
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util.debug('doing self._thread.start()')
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self._thread.start()
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util.debug('... done self._thread.start()')
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# On process exit we will wait for data to be flushed to pipe.
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#
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# However, if this process created the queue then all
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# processes which use the queue will be descendants of this
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# process. Therefore waiting for the queue to be flushed
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# is pointless once all the child processes have been joined.
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created_by_this_process = (self._opid == os.getpid())
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if not self._joincancelled and not created_by_this_process:
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self._jointhread = util.Finalize(
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self._thread, Queue._finalize_join,
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[weakref.ref(self._thread)],
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exitpriority=-5
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)
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# Send sentinel to the thread queue object when garbage collected
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self._close = util.Finalize(
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self, Queue._finalize_close,
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[self._buffer, self._notempty],
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exitpriority=10
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)
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# Overload the _feed methods to use our custom pickling strategy.
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@staticmethod
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def _feed(buffer, notempty, send_bytes, writelock, close, reducers,
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ignore_epipe, onerror, queue_sem):
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util.debug('starting thread to feed data to pipe')
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nacquire = notempty.acquire
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nrelease = notempty.release
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nwait = notempty.wait
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bpopleft = buffer.popleft
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sentinel = _sentinel
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if sys.platform != 'win32':
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wacquire = writelock.acquire
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wrelease = writelock.release
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else:
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wacquire = None
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while 1:
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try:
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nacquire()
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try:
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if not buffer:
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nwait()
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finally:
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nrelease()
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try:
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while 1:
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obj = bpopleft()
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if obj is sentinel:
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util.debug('feeder thread got sentinel -- exiting')
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close()
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return
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# serialize the data before acquiring the lock
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obj_ = dumps(obj, reducers=reducers)
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if wacquire is None:
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send_bytes(obj_)
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else:
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wacquire()
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try:
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send_bytes(obj_)
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finally:
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wrelease()
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# Remove references early to avoid leaking memory
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del obj, obj_
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except IndexError:
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pass
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except BaseException as e:
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if ignore_epipe and getattr(e, 'errno', 0) == errno.EPIPE:
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return
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# Since this runs in a daemon thread the resources it uses
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# may be become unusable while the process is cleaning up.
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# We ignore errors which happen after the process has
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# started to cleanup.
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if util.is_exiting():
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util.info('error in queue thread: %s', e)
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return
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else:
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queue_sem.release()
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onerror(e, obj)
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def _on_queue_feeder_error(self, e, obj):
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"""
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Private API hook called when feeding data in the background thread
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raises an exception. For overriding by concurrent.futures.
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"""
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import traceback
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traceback.print_exc()
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if sys.version_info[:2] < (3, 4):
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# Compat for python2.7/3.3 that use _send instead of _send_bytes
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def _after_fork(self):
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super(Queue, self)._after_fork()
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self._send_bytes = self._writer.send_bytes
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class SimpleQueue(mp_SimpleQueue):
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def __init__(self, reducers=None, ctx=None):
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if sys.version_info[:2] >= (3, 4):
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super().__init__(ctx=ctx)
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else:
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# Use the context to create the sync objects for python2.7/3.3
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if ctx is None:
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ctx = get_context()
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self._reader, self._writer = connection.Pipe(duplex=False)
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self._rlock = ctx.Lock()
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self._poll = self._reader.poll
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if sys.platform == 'win32':
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self._wlock = None
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else:
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self._wlock = ctx.Lock()
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# Add possiblity to use custom reducers
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self._reducers = reducers
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# Use custom queue set/get state to be able to reduce the custom reducers
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def __getstate__(self):
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assert_spawning(self)
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return (self._reader, self._writer, self._reducers, self._rlock,
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self._wlock)
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def __setstate__(self, state):
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(self._reader, self._writer, self._reducers, self._rlock,
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self._wlock) = state
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if sys.version_info[:2] < (3, 4):
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# For python2.7/3.3, overload get to avoid creating deadlocks with
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# unpickling errors.
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def get(self):
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with self._rlock:
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res = self._reader.recv_bytes()
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# unserialize the data after having released the lock
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return loads(res)
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# Overload put to use our customizable reducer
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def put(self, obj):
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# serialize the data before acquiring the lock
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obj = dumps(obj, reducers=self._reducers)
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if self._wlock is None:
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# writes to a message oriented win32 pipe are atomic
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self._writer.send_bytes(obj)
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else:
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with self._wlock:
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self._writer.send_bytes(obj)
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