mirror of https://github.com/python/cpython
373 lines
11 KiB
Python
373 lines
11 KiB
Python
#
|
|
# Module implementing queues
|
|
#
|
|
# multiprocessing/queues.py
|
|
#
|
|
# Copyright (c) 2006-2008, R Oudkerk
|
|
# Licensed to PSF under a Contributor Agreement.
|
|
#
|
|
|
|
__all__ = ['Queue', 'SimpleQueue', 'JoinableQueue']
|
|
|
|
import sys
|
|
import os
|
|
import threading
|
|
import collections
|
|
import time
|
|
import weakref
|
|
import errno
|
|
|
|
from queue import Empty, Full
|
|
|
|
import _multiprocessing
|
|
|
|
from . import connection
|
|
from . import context
|
|
|
|
from .util import debug, info, Finalize, register_after_fork, is_exiting
|
|
from .reduction import ForkingPickler
|
|
|
|
#
|
|
# Queue type using a pipe, buffer and thread
|
|
#
|
|
|
|
class Queue(object):
|
|
|
|
def __init__(self, maxsize=0, *, ctx):
|
|
if maxsize <= 0:
|
|
# Can raise ImportError (see issues #3770 and #23400)
|
|
from .synchronize import SEM_VALUE_MAX as maxsize
|
|
self._maxsize = maxsize
|
|
self._reader, self._writer = connection.Pipe(duplex=False)
|
|
self._rlock = ctx.Lock()
|
|
self._opid = os.getpid()
|
|
if sys.platform == 'win32':
|
|
self._wlock = None
|
|
else:
|
|
self._wlock = ctx.Lock()
|
|
self._sem = ctx.BoundedSemaphore(maxsize)
|
|
# For use by concurrent.futures
|
|
self._ignore_epipe = False
|
|
|
|
self._after_fork()
|
|
|
|
if sys.platform != 'win32':
|
|
register_after_fork(self, Queue._after_fork)
|
|
|
|
def __getstate__(self):
|
|
context.assert_spawning(self)
|
|
return (self._ignore_epipe, self._maxsize, self._reader, self._writer,
|
|
self._rlock, self._wlock, self._sem, self._opid)
|
|
|
|
def __setstate__(self, state):
|
|
(self._ignore_epipe, self._maxsize, self._reader, self._writer,
|
|
self._rlock, self._wlock, self._sem, self._opid) = state
|
|
self._after_fork()
|
|
|
|
def _after_fork(self):
|
|
debug('Queue._after_fork()')
|
|
self._notempty = threading.Condition(threading.Lock())
|
|
self._buffer = collections.deque()
|
|
self._thread = None
|
|
self._jointhread = None
|
|
self._joincancelled = False
|
|
self._closed = False
|
|
self._close = None
|
|
self._send_bytes = self._writer.send_bytes
|
|
self._recv_bytes = self._reader.recv_bytes
|
|
self._poll = self._reader.poll
|
|
|
|
def put(self, obj, block=True, timeout=None):
|
|
assert not self._closed
|
|
if not self._sem.acquire(block, timeout):
|
|
raise Full
|
|
|
|
self._notempty.acquire()
|
|
try:
|
|
if self._thread is None:
|
|
self._start_thread()
|
|
self._buffer.append(obj)
|
|
self._notempty.notify()
|
|
finally:
|
|
self._notempty.release()
|
|
|
|
def get(self, block=True, timeout=None):
|
|
if block and timeout is None:
|
|
with self._rlock:
|
|
res = self._recv_bytes()
|
|
self._sem.release()
|
|
else:
|
|
if block:
|
|
deadline = time.time() + timeout
|
|
if not self._rlock.acquire(block, timeout):
|
|
raise Empty
|
|
try:
|
|
if block:
|
|
timeout = deadline - time.time()
|
|
if timeout < 0 or not self._poll(timeout):
|
|
raise Empty
|
|
elif not self._poll():
|
|
raise Empty
|
|
res = self._recv_bytes()
|
|
self._sem.release()
|
|
finally:
|
|
self._rlock.release()
|
|
# unserialize the data after having released the lock
|
|
return ForkingPickler.loads(res)
|
|
|
|
def qsize(self):
|
|
# Raises NotImplementedError on Mac OSX because of broken sem_getvalue()
|
|
return self._maxsize - self._sem._semlock._get_value()
|
|
|
|
def empty(self):
|
|
return not self._poll()
|
|
|
|
def full(self):
|
|
return self._sem._semlock._is_zero()
|
|
|
|
def get_nowait(self):
|
|
return self.get(False)
|
|
|
|
def put_nowait(self, obj):
|
|
return self.put(obj, False)
|
|
|
|
def close(self):
|
|
self._closed = True
|
|
try:
|
|
self._reader.close()
|
|
finally:
|
|
close = self._close
|
|
if close:
|
|
self._close = None
|
|
close()
|
|
|
|
def join_thread(self):
|
|
debug('Queue.join_thread()')
|
|
assert self._closed
|
|
if self._jointhread:
|
|
self._jointhread()
|
|
|
|
def cancel_join_thread(self):
|
|
debug('Queue.cancel_join_thread()')
|
|
self._joincancelled = True
|
|
try:
|
|
self._jointhread.cancel()
|
|
except AttributeError:
|
|
pass
|
|
|
|
def _start_thread(self):
|
|
debug('Queue._start_thread()')
|
|
|
|
# Start thread which transfers data from buffer to pipe
|
|
self._buffer.clear()
|
|
self._thread = threading.Thread(
|
|
target=Queue._feed,
|
|
args=(self._buffer, self._notempty, self._send_bytes,
|
|
self._wlock, self._writer.close, self._ignore_epipe),
|
|
name='QueueFeederThread'
|
|
)
|
|
self._thread.daemon = True
|
|
|
|
debug('doing self._thread.start()')
|
|
self._thread.start()
|
|
debug('... done self._thread.start()')
|
|
|
|
# On process exit we will wait for data to be flushed to pipe.
|
|
#
|
|
# However, if this process created the queue then all
|
|
# processes which use the queue will be descendants of this
|
|
# process. Therefore waiting for the queue to be flushed
|
|
# is pointless once all the child processes have been joined.
|
|
created_by_this_process = (self._opid == os.getpid())
|
|
if not self._joincancelled and not created_by_this_process:
|
|
self._jointhread = Finalize(
|
|
self._thread, Queue._finalize_join,
|
|
[weakref.ref(self._thread)],
|
|
exitpriority=-5
|
|
)
|
|
|
|
# Send sentinel to the thread queue object when garbage collected
|
|
self._close = Finalize(
|
|
self, Queue._finalize_close,
|
|
[self._buffer, self._notempty],
|
|
exitpriority=10
|
|
)
|
|
|
|
@staticmethod
|
|
def _finalize_join(twr):
|
|
debug('joining queue thread')
|
|
thread = twr()
|
|
if thread is not None:
|
|
thread.join()
|
|
debug('... queue thread joined')
|
|
else:
|
|
debug('... queue thread already dead')
|
|
|
|
@staticmethod
|
|
def _finalize_close(buffer, notempty):
|
|
debug('telling queue thread to quit')
|
|
notempty.acquire()
|
|
try:
|
|
buffer.append(_sentinel)
|
|
notempty.notify()
|
|
finally:
|
|
notempty.release()
|
|
|
|
@staticmethod
|
|
def _feed(buffer, notempty, send_bytes, writelock, close, ignore_epipe):
|
|
debug('starting thread to feed data to pipe')
|
|
nacquire = notempty.acquire
|
|
nrelease = notempty.release
|
|
nwait = notempty.wait
|
|
bpopleft = buffer.popleft
|
|
sentinel = _sentinel
|
|
if sys.platform != 'win32':
|
|
wacquire = writelock.acquire
|
|
wrelease = writelock.release
|
|
else:
|
|
wacquire = None
|
|
|
|
try:
|
|
while 1:
|
|
nacquire()
|
|
try:
|
|
if not buffer:
|
|
nwait()
|
|
finally:
|
|
nrelease()
|
|
try:
|
|
while 1:
|
|
obj = bpopleft()
|
|
if obj is sentinel:
|
|
debug('feeder thread got sentinel -- exiting')
|
|
close()
|
|
return
|
|
|
|
# serialize the data before acquiring the lock
|
|
obj = ForkingPickler.dumps(obj)
|
|
if wacquire is None:
|
|
send_bytes(obj)
|
|
else:
|
|
wacquire()
|
|
try:
|
|
send_bytes(obj)
|
|
finally:
|
|
wrelease()
|
|
except IndexError:
|
|
pass
|
|
except Exception as e:
|
|
if ignore_epipe and getattr(e, 'errno', 0) == errno.EPIPE:
|
|
return
|
|
# Since this runs in a daemon thread the resources it uses
|
|
# may be become unusable while the process is cleaning up.
|
|
# We ignore errors which happen after the process has
|
|
# started to cleanup.
|
|
try:
|
|
if is_exiting():
|
|
info('error in queue thread: %s', e)
|
|
else:
|
|
import traceback
|
|
traceback.print_exc()
|
|
except Exception:
|
|
pass
|
|
|
|
_sentinel = object()
|
|
|
|
#
|
|
# A queue type which also supports join() and task_done() methods
|
|
#
|
|
# Note that if you do not call task_done() for each finished task then
|
|
# eventually the counter's semaphore may overflow causing Bad Things
|
|
# to happen.
|
|
#
|
|
|
|
class JoinableQueue(Queue):
|
|
|
|
def __init__(self, maxsize=0, *, ctx):
|
|
Queue.__init__(self, maxsize, ctx=ctx)
|
|
self._unfinished_tasks = ctx.Semaphore(0)
|
|
self._cond = ctx.Condition()
|
|
|
|
def __getstate__(self):
|
|
return Queue.__getstate__(self) + (self._cond, self._unfinished_tasks)
|
|
|
|
def __setstate__(self, state):
|
|
Queue.__setstate__(self, state[:-2])
|
|
self._cond, self._unfinished_tasks = state[-2:]
|
|
|
|
def put(self, obj, block=True, timeout=None):
|
|
assert not self._closed
|
|
if not self._sem.acquire(block, timeout):
|
|
raise Full
|
|
|
|
self._notempty.acquire()
|
|
self._cond.acquire()
|
|
try:
|
|
if self._thread is None:
|
|
self._start_thread()
|
|
self._buffer.append(obj)
|
|
self._unfinished_tasks.release()
|
|
self._notempty.notify()
|
|
finally:
|
|
self._cond.release()
|
|
self._notempty.release()
|
|
|
|
def task_done(self):
|
|
self._cond.acquire()
|
|
try:
|
|
if not self._unfinished_tasks.acquire(False):
|
|
raise ValueError('task_done() called too many times')
|
|
if self._unfinished_tasks._semlock._is_zero():
|
|
self._cond.notify_all()
|
|
finally:
|
|
self._cond.release()
|
|
|
|
def join(self):
|
|
self._cond.acquire()
|
|
try:
|
|
if not self._unfinished_tasks._semlock._is_zero():
|
|
self._cond.wait()
|
|
finally:
|
|
self._cond.release()
|
|
|
|
#
|
|
# Simplified Queue type -- really just a locked pipe
|
|
#
|
|
|
|
class SimpleQueue(object):
|
|
|
|
def __init__(self, *, ctx):
|
|
self._reader, self._writer = connection.Pipe(duplex=False)
|
|
self._rlock = ctx.Lock()
|
|
self._poll = self._reader.poll
|
|
if sys.platform == 'win32':
|
|
self._wlock = None
|
|
else:
|
|
self._wlock = ctx.Lock()
|
|
|
|
def empty(self):
|
|
return not self._poll()
|
|
|
|
def __getstate__(self):
|
|
context.assert_spawning(self)
|
|
return (self._reader, self._writer, self._rlock, self._wlock)
|
|
|
|
def __setstate__(self, state):
|
|
(self._reader, self._writer, self._rlock, self._wlock) = state
|
|
|
|
def get(self):
|
|
with self._rlock:
|
|
res = self._reader.recv_bytes()
|
|
# unserialize the data after having released the lock
|
|
return ForkingPickler.loads(res)
|
|
|
|
def put(self, obj):
|
|
# serialize the data before acquiring the lock
|
|
obj = ForkingPickler.dumps(obj)
|
|
if self._wlock is None:
|
|
# writes to a message oriented win32 pipe are atomic
|
|
self._writer.send_bytes(obj)
|
|
else:
|
|
with self._wlock:
|
|
self._writer.send_bytes(obj)
|