You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
787 lines
31 KiB
787 lines
31 KiB
2 years ago
|
# Copyright 2009 Brian Quinlan. All Rights Reserved.
|
||
|
|
# Licensed to PSF under a Contributor Agreement.
|
||
|
|
|
||
|
|
"""Implements ProcessPoolExecutor.
|
||
|
|
|
||
|
|
The following diagram and text describe the data-flow through the system:
|
||
|
|
|
||
|
|
|======================= In-process =====================|== Out-of-process ==|
|
||
|
|
|
||
|
|
+----------+ +----------+ +--------+ +-----------+ +---------+
|
||
|
|
| | => | Work Ids | | | | Call Q | | Process |
|
||
|
|
| | +----------+ | | +-----------+ | Pool |
|
||
|
|
| | | ... | | | | ... | +---------+
|
||
|
|
| | | 6 | => | | => | 5, call() | => | |
|
||
|
|
| | | 7 | | | | ... | | |
|
||
|
|
| Process | | ... | | Local | +-----------+ | Process |
|
||
|
|
| Pool | +----------+ | Worker | | #1..n |
|
||
|
|
| Executor | | Thread | | |
|
||
|
|
| | +----------- + | | +-----------+ | |
|
||
|
|
| | <=> | Work Items | <=> | | <= | Result Q | <= | |
|
||
|
|
| | +------------+ | | +-----------+ | |
|
||
|
|
| | | 6: call() | | | | ... | | |
|
||
|
|
| | | future | | | | 4, result | | |
|
||
|
|
| | | ... | | | | 3, except | | |
|
||
|
|
+----------+ +------------+ +--------+ +-----------+ +---------+
|
||
|
|
|
||
|
|
Executor.submit() called:
|
||
|
|
- creates a uniquely numbered _WorkItem and adds it to the "Work Items" dict
|
||
|
|
- adds the id of the _WorkItem to the "Work Ids" queue
|
||
|
|
|
||
|
|
Local worker thread:
|
||
|
|
- reads work ids from the "Work Ids" queue and looks up the corresponding
|
||
|
|
WorkItem from the "Work Items" dict: if the work item has been cancelled then
|
||
|
|
it is simply removed from the dict, otherwise it is repackaged as a
|
||
|
|
_CallItem and put in the "Call Q". New _CallItems are put in the "Call Q"
|
||
|
|
until "Call Q" is full. NOTE: the size of the "Call Q" is kept small because
|
||
|
|
calls placed in the "Call Q" can no longer be cancelled with Future.cancel().
|
||
|
|
- reads _ResultItems from "Result Q", updates the future stored in the
|
||
|
|
"Work Items" dict and deletes the dict entry
|
||
|
|
|
||
|
|
Process #1..n:
|
||
|
|
- reads _CallItems from "Call Q", executes the calls, and puts the resulting
|
||
|
|
_ResultItems in "Result Q"
|
||
|
|
"""
|
||
|
|
|
||
|
|
__author__ = 'Brian Quinlan (brian@sweetapp.com)'
|
||
|
|
|
||
|
|
import os
|
||
|
|
from concurrent.futures import _base
|
||
|
|
import queue
|
||
|
|
import multiprocessing as mp
|
||
|
|
import multiprocessing.connection
|
||
|
|
from multiprocessing.queues import Queue
|
||
|
|
import threading
|
||
|
|
import weakref
|
||
|
|
from functools import partial
|
||
|
|
import itertools
|
||
|
|
import sys
|
||
|
|
import traceback
|
||
|
|
|
||
|
|
|
||
|
|
_threads_wakeups = weakref.WeakKeyDictionary()
|
||
|
|
_global_shutdown = False
|
||
|
|
|
||
|
|
|
||
|
|
class _ThreadWakeup:
|
||
|
|
def __init__(self):
|
||
|
|
self._closed = False
|
||
|
|
self._reader, self._writer = mp.Pipe(duplex=False)
|
||
|
|
|
||
|
|
def close(self):
|
||
|
|
if not self._closed:
|
||
|
|
self._closed = True
|
||
|
|
self._writer.close()
|
||
|
|
self._reader.close()
|
||
|
|
|
||
|
|
def wakeup(self):
|
||
|
|
if not self._closed:
|
||
|
|
self._writer.send_bytes(b"")
|
||
|
|
|
||
|
|
def clear(self):
|
||
|
|
if not self._closed:
|
||
|
|
while self._reader.poll():
|
||
|
|
self._reader.recv_bytes()
|
||
|
|
|
||
|
|
|
||
|
|
def _python_exit():
|
||
|
|
global _global_shutdown
|
||
|
|
_global_shutdown = True
|
||
|
|
items = list(_threads_wakeups.items())
|
||
|
|
for _, thread_wakeup in items:
|
||
|
|
# call not protected by ProcessPoolExecutor._shutdown_lock
|
||
|
|
thread_wakeup.wakeup()
|
||
|
|
for t, _ in items:
|
||
|
|
t.join()
|
||
|
|
|
||
|
|
# Register for `_python_exit()` to be called just before joining all
|
||
|
|
# non-daemon threads. This is used instead of `atexit.register()` for
|
||
|
|
# compatibility with subinterpreters, which no longer support daemon threads.
|
||
|
|
# See bpo-39812 for context.
|
||
|
|
threading._register_atexit(_python_exit)
|
||
|
|
|
||
|
|
# Controls how many more calls than processes will be queued in the call queue.
|
||
|
|
# A smaller number will mean that processes spend more time idle waiting for
|
||
|
|
# work while a larger number will make Future.cancel() succeed less frequently
|
||
|
|
# (Futures in the call queue cannot be cancelled).
|
||
|
|
EXTRA_QUEUED_CALLS = 1
|
||
|
|
|
||
|
|
|
||
|
|
# On Windows, WaitForMultipleObjects is used to wait for processes to finish.
|
||
|
|
# It can wait on, at most, 63 objects. There is an overhead of two objects:
|
||
|
|
# - the result queue reader
|
||
|
|
# - the thread wakeup reader
|
||
|
|
_MAX_WINDOWS_WORKERS = 63 - 2
|
||
|
|
|
||
|
|
# Hack to embed stringification of remote traceback in local traceback
|
||
|
|
|
||
|
|
class _RemoteTraceback(Exception):
|
||
|
|
def __init__(self, tb):
|
||
|
|
self.tb = tb
|
||
|
|
def __str__(self):
|
||
|
|
return self.tb
|
||
|
|
|
||
|
|
class _ExceptionWithTraceback:
|
||
|
|
def __init__(self, exc, tb):
|
||
|
|
tb = traceback.format_exception(type(exc), exc, tb)
|
||
|
|
tb = ''.join(tb)
|
||
|
|
self.exc = exc
|
||
|
|
# Traceback object needs to be garbage-collected as its frames
|
||
|
|
# contain references to all the objects in the exception scope
|
||
|
|
self.exc.__traceback__ = None
|
||
|
|
self.tb = '\n"""\n%s"""' % tb
|
||
|
|
def __reduce__(self):
|
||
|
|
return _rebuild_exc, (self.exc, self.tb)
|
||
|
|
|
||
|
|
def _rebuild_exc(exc, tb):
|
||
|
|
exc.__cause__ = _RemoteTraceback(tb)
|
||
|
|
return exc
|
||
|
|
|
||
|
|
class _WorkItem(object):
|
||
|
|
def __init__(self, future, fn, args, kwargs):
|
||
|
|
self.future = future
|
||
|
|
self.fn = fn
|
||
|
|
self.args = args
|
||
|
|
self.kwargs = kwargs
|
||
|
|
|
||
|
|
class _ResultItem(object):
|
||
|
|
def __init__(self, work_id, exception=None, result=None):
|
||
|
|
self.work_id = work_id
|
||
|
|
self.exception = exception
|
||
|
|
self.result = result
|
||
|
|
|
||
|
|
class _CallItem(object):
|
||
|
|
def __init__(self, work_id, fn, args, kwargs):
|
||
|
|
self.work_id = work_id
|
||
|
|
self.fn = fn
|
||
|
|
self.args = args
|
||
|
|
self.kwargs = kwargs
|
||
|
|
|
||
|
|
|
||
|
|
class _SafeQueue(Queue):
|
||
|
|
"""Safe Queue set exception to the future object linked to a job"""
|
||
|
|
def __init__(self, max_size=0, *, ctx, pending_work_items, shutdown_lock,
|
||
|
|
thread_wakeup):
|
||
|
|
self.pending_work_items = pending_work_items
|
||
|
|
self.shutdown_lock = shutdown_lock
|
||
|
|
self.thread_wakeup = thread_wakeup
|
||
|
|
super().__init__(max_size, ctx=ctx)
|
||
|
|
|
||
|
|
def _on_queue_feeder_error(self, e, obj):
|
||
|
|
if isinstance(obj, _CallItem):
|
||
|
|
tb = traceback.format_exception(type(e), e, e.__traceback__)
|
||
|
|
e.__cause__ = _RemoteTraceback('\n"""\n{}"""'.format(''.join(tb)))
|
||
|
|
work_item = self.pending_work_items.pop(obj.work_id, None)
|
||
|
|
with self.shutdown_lock:
|
||
|
|
self.thread_wakeup.wakeup()
|
||
|
|
# work_item can be None if another process terminated. In this
|
||
|
|
# case, the executor_manager_thread fails all work_items
|
||
|
|
# with BrokenProcessPool
|
||
|
|
if work_item is not None:
|
||
|
|
work_item.future.set_exception(e)
|
||
|
|
else:
|
||
|
|
super()._on_queue_feeder_error(e, obj)
|
||
|
|
|
||
|
|
|
||
|
|
def _get_chunks(*iterables, chunksize):
|
||
|
|
""" Iterates over zip()ed iterables in chunks. """
|
||
|
|
it = zip(*iterables)
|
||
|
|
while True:
|
||
|
|
chunk = tuple(itertools.islice(it, chunksize))
|
||
|
|
if not chunk:
|
||
|
|
return
|
||
|
|
yield chunk
|
||
|
|
|
||
|
|
|
||
|
|
def _process_chunk(fn, chunk):
|
||
|
|
""" Processes a chunk of an iterable passed to map.
|
||
|
|
|
||
|
|
Runs the function passed to map() on a chunk of the
|
||
|
|
iterable passed to map.
|
||
|
|
|
||
|
|
This function is run in a separate process.
|
||
|
|
|
||
|
|
"""
|
||
|
|
return [fn(*args) for args in chunk]
|
||
|
|
|
||
|
|
|
||
|
|
def _sendback_result(result_queue, work_id, result=None, exception=None):
|
||
|
|
"""Safely send back the given result or exception"""
|
||
|
|
try:
|
||
|
|
result_queue.put(_ResultItem(work_id, result=result,
|
||
|
|
exception=exception))
|
||
|
|
except BaseException as e:
|
||
|
|
exc = _ExceptionWithTraceback(e, e.__traceback__)
|
||
|
|
result_queue.put(_ResultItem(work_id, exception=exc))
|
||
|
|
|
||
|
|
|
||
|
|
def _process_worker(call_queue, result_queue, initializer, initargs):
|
||
|
|
"""Evaluates calls from call_queue and places the results in result_queue.
|
||
|
|
|
||
|
|
This worker is run in a separate process.
|
||
|
|
|
||
|
|
Args:
|
||
|
|
call_queue: A ctx.Queue of _CallItems that will be read and
|
||
|
|
evaluated by the worker.
|
||
|
|
result_queue: A ctx.Queue of _ResultItems that will written
|
||
|
|
to by the worker.
|
||
|
|
initializer: A callable initializer, or None
|
||
|
|
initargs: A tuple of args for the initializer
|
||
|
|
"""
|
||
|
|
if initializer is not None:
|
||
|
|
try:
|
||
|
|
initializer(*initargs)
|
||
|
|
except BaseException:
|
||
|
|
_base.LOGGER.critical('Exception in initializer:', exc_info=True)
|
||
|
|
# The parent will notice that the process stopped and
|
||
|
|
# mark the pool broken
|
||
|
|
return
|
||
|
|
while True:
|
||
|
|
call_item = call_queue.get(block=True)
|
||
|
|
if call_item is None:
|
||
|
|
# Wake up queue management thread
|
||
|
|
result_queue.put(os.getpid())
|
||
|
|
return
|
||
|
|
try:
|
||
|
|
r = call_item.fn(*call_item.args, **call_item.kwargs)
|
||
|
|
except BaseException as e:
|
||
|
|
exc = _ExceptionWithTraceback(e, e.__traceback__)
|
||
|
|
_sendback_result(result_queue, call_item.work_id, exception=exc)
|
||
|
|
else:
|
||
|
|
_sendback_result(result_queue, call_item.work_id, result=r)
|
||
|
|
del r
|
||
|
|
|
||
|
|
# Liberate the resource as soon as possible, to avoid holding onto
|
||
|
|
# open files or shared memory that is not needed anymore
|
||
|
|
del call_item
|
||
|
|
|
||
|
|
|
||
|
|
class _ExecutorManagerThread(threading.Thread):
|
||
|
|
"""Manages the communication between this process and the worker processes.
|
||
|
|
|
||
|
|
The manager is run in a local thread.
|
||
|
|
|
||
|
|
Args:
|
||
|
|
executor: A reference to the ProcessPoolExecutor that owns
|
||
|
|
this thread. A weakref will be own by the manager as well as
|
||
|
|
references to internal objects used to introspect the state of
|
||
|
|
the executor.
|
||
|
|
"""
|
||
|
|
|
||
|
|
def __init__(self, executor):
|
||
|
|
# Store references to necessary internals of the executor.
|
||
|
|
|
||
|
|
# A _ThreadWakeup to allow waking up the queue_manager_thread from the
|
||
|
|
# main Thread and avoid deadlocks caused by permanently locked queues.
|
||
|
|
self.thread_wakeup = executor._executor_manager_thread_wakeup
|
||
|
|
self.shutdown_lock = executor._shutdown_lock
|
||
|
|
|
||
|
|
# A weakref.ref to the ProcessPoolExecutor that owns this thread. Used
|
||
|
|
# to determine if the ProcessPoolExecutor has been garbage collected
|
||
|
|
# and that the manager can exit.
|
||
|
|
# When the executor gets garbage collected, the weakref callback
|
||
|
|
# will wake up the queue management thread so that it can terminate
|
||
|
|
# if there is no pending work item.
|
||
|
|
def weakref_cb(_,
|
||
|
|
thread_wakeup=self.thread_wakeup,
|
||
|
|
shutdown_lock=self.shutdown_lock):
|
||
|
|
mp.util.debug('Executor collected: triggering callback for'
|
||
|
|
' QueueManager wakeup')
|
||
|
|
with shutdown_lock:
|
||
|
|
thread_wakeup.wakeup()
|
||
|
|
|
||
|
|
self.executor_reference = weakref.ref(executor, weakref_cb)
|
||
|
|
|
||
|
|
# A list of the ctx.Process instances used as workers.
|
||
|
|
self.processes = executor._processes
|
||
|
|
|
||
|
|
# A ctx.Queue that will be filled with _CallItems derived from
|
||
|
|
# _WorkItems for processing by the process workers.
|
||
|
|
self.call_queue = executor._call_queue
|
||
|
|
|
||
|
|
# A ctx.SimpleQueue of _ResultItems generated by the process workers.
|
||
|
|
self.result_queue = executor._result_queue
|
||
|
|
|
||
|
|
# A queue.Queue of work ids e.g. Queue([5, 6, ...]).
|
||
|
|
self.work_ids_queue = executor._work_ids
|
||
|
|
|
||
|
|
# A dict mapping work ids to _WorkItems e.g.
|
||
|
|
# {5: <_WorkItem...>, 6: <_WorkItem...>, ...}
|
||
|
|
self.pending_work_items = executor._pending_work_items
|
||
|
|
|
||
|
|
super().__init__()
|
||
|
|
|
||
|
|
def run(self):
|
||
|
|
# Main loop for the executor manager thread.
|
||
|
|
|
||
|
|
while True:
|
||
|
|
self.add_call_item_to_queue()
|
||
|
|
|
||
|
|
result_item, is_broken, cause = self.wait_result_broken_or_wakeup()
|
||
|
|
|
||
|
|
if is_broken:
|
||
|
|
self.terminate_broken(cause)
|
||
|
|
return
|
||
|
|
if result_item is not None:
|
||
|
|
self.process_result_item(result_item)
|
||
|
|
# Delete reference to result_item to avoid keeping references
|
||
|
|
# while waiting on new results.
|
||
|
|
del result_item
|
||
|
|
|
||
|
|
# attempt to increment idle process count
|
||
|
|
executor = self.executor_reference()
|
||
|
|
if executor is not None:
|
||
|
|
executor._idle_worker_semaphore.release()
|
||
|
|
del executor
|
||
|
|
|
||
|
|
if self.is_shutting_down():
|
||
|
|
self.flag_executor_shutting_down()
|
||
|
|
|
||
|
|
# Since no new work items can be added, it is safe to shutdown
|
||
|
|
# this thread if there are no pending work items.
|
||
|
|
if not self.pending_work_items:
|
||
|
|
self.join_executor_internals()
|
||
|
|
return
|
||
|
|
|
||
|
|
def add_call_item_to_queue(self):
|
||
|
|
# Fills call_queue with _WorkItems from pending_work_items.
|
||
|
|
# This function never blocks.
|
||
|
|
while True:
|
||
|
|
if self.call_queue.full():
|
||
|
|
return
|
||
|
|
try:
|
||
|
|
work_id = self.work_ids_queue.get(block=False)
|
||
|
|
except queue.Empty:
|
||
|
|
return
|
||
|
|
else:
|
||
|
|
work_item = self.pending_work_items[work_id]
|
||
|
|
|
||
|
|
if work_item.future.set_running_or_notify_cancel():
|
||
|
|
self.call_queue.put(_CallItem(work_id,
|
||
|
|
work_item.fn,
|
||
|
|
work_item.args,
|
||
|
|
work_item.kwargs),
|
||
|
|
block=True)
|
||
|
|
else:
|
||
|
|
del self.pending_work_items[work_id]
|
||
|
|
continue
|
||
|
|
|
||
|
|
def wait_result_broken_or_wakeup(self):
|
||
|
|
# Wait for a result to be ready in the result_queue while checking
|
||
|
|
# that all worker processes are still running, or for a wake up
|
||
|
|
# signal send. The wake up signals come either from new tasks being
|
||
|
|
# submitted, from the executor being shutdown/gc-ed, or from the
|
||
|
|
# shutdown of the python interpreter.
|
||
|
|
result_reader = self.result_queue._reader
|
||
|
|
assert not self.thread_wakeup._closed
|
||
|
|
wakeup_reader = self.thread_wakeup._reader
|
||
|
|
readers = [result_reader, wakeup_reader]
|
||
|
|
worker_sentinels = [p.sentinel for p in list(self.processes.values())]
|
||
|
|
ready = mp.connection.wait(readers + worker_sentinels)
|
||
|
|
|
||
|
|
cause = None
|
||
|
|
is_broken = True
|
||
|
|
result_item = None
|
||
|
|
if result_reader in ready:
|
||
|
|
try:
|
||
|
|
result_item = result_reader.recv()
|
||
|
|
is_broken = False
|
||
|
|
except BaseException as e:
|
||
|
|
cause = traceback.format_exception(type(e), e, e.__traceback__)
|
||
|
|
|
||
|
|
elif wakeup_reader in ready:
|
||
|
|
is_broken = False
|
||
|
|
|
||
|
|
with self.shutdown_lock:
|
||
|
|
self.thread_wakeup.clear()
|
||
|
|
|
||
|
|
return result_item, is_broken, cause
|
||
|
|
|
||
|
|
def process_result_item(self, result_item):
|
||
|
|
# Process the received a result_item. This can be either the PID of a
|
||
|
|
# worker that exited gracefully or a _ResultItem
|
||
|
|
|
||
|
|
if isinstance(result_item, int):
|
||
|
|
# Clean shutdown of a worker using its PID
|
||
|
|
# (avoids marking the executor broken)
|
||
|
|
assert self.is_shutting_down()
|
||
|
|
p = self.processes.pop(result_item)
|
||
|
|
p.join()
|
||
|
|
if not self.processes:
|
||
|
|
self.join_executor_internals()
|
||
|
|
return
|
||
|
|
else:
|
||
|
|
# Received a _ResultItem so mark the future as completed.
|
||
|
|
work_item = self.pending_work_items.pop(result_item.work_id, None)
|
||
|
|
# work_item can be None if another process terminated (see above)
|
||
|
|
if work_item is not None:
|
||
|
|
if result_item.exception:
|
||
|
|
work_item.future.set_exception(result_item.exception)
|
||
|
|
else:
|
||
|
|
work_item.future.set_result(result_item.result)
|
||
|
|
|
||
|
|
def is_shutting_down(self):
|
||
|
|
# Check whether we should start shutting down the executor.
|
||
|
|
executor = self.executor_reference()
|
||
|
|
# No more work items can be added if:
|
||
|
|
# - The interpreter is shutting down OR
|
||
|
|
# - The executor that owns this worker has been collected OR
|
||
|
|
# - The executor that owns this worker has been shutdown.
|
||
|
|
return (_global_shutdown or executor is None
|
||
|
|
or executor._shutdown_thread)
|
||
|
|
|
||
|
|
def terminate_broken(self, cause):
|
||
|
|
# Terminate the executor because it is in a broken state. The cause
|
||
|
|
# argument can be used to display more information on the error that
|
||
|
|
# lead the executor into becoming broken.
|
||
|
|
|
||
|
|
# Mark the process pool broken so that submits fail right now.
|
||
|
|
executor = self.executor_reference()
|
||
|
|
if executor is not None:
|
||
|
|
executor._broken = ('A child process terminated '
|
||
|
|
'abruptly, the process pool is not '
|
||
|
|
'usable anymore')
|
||
|
|
executor._shutdown_thread = True
|
||
|
|
executor = None
|
||
|
|
|
||
|
|
# All pending tasks are to be marked failed with the following
|
||
|
|
# BrokenProcessPool error
|
||
|
|
bpe = BrokenProcessPool("A process in the process pool was "
|
||
|
|
"terminated abruptly while the future was "
|
||
|
|
"running or pending.")
|
||
|
|
if cause is not None:
|
||
|
|
bpe.__cause__ = _RemoteTraceback(
|
||
|
|
f"\n'''\n{''.join(cause)}'''")
|
||
|
|
|
||
|
|
# Mark pending tasks as failed.
|
||
|
|
for work_id, work_item in self.pending_work_items.items():
|
||
|
|
work_item.future.set_exception(bpe)
|
||
|
|
# Delete references to object. See issue16284
|
||
|
|
del work_item
|
||
|
|
self.pending_work_items.clear()
|
||
|
|
|
||
|
|
# Terminate remaining workers forcibly: the queues or their
|
||
|
|
# locks may be in a dirty state and block forever.
|
||
|
|
for p in self.processes.values():
|
||
|
|
p.terminate()
|
||
|
|
|
||
|
|
# clean up resources
|
||
|
|
self.join_executor_internals()
|
||
|
|
|
||
|
|
def flag_executor_shutting_down(self):
|
||
|
|
# Flag the executor as shutting down and cancel remaining tasks if
|
||
|
|
# requested as early as possible if it is not gc-ed yet.
|
||
|
|
executor = self.executor_reference()
|
||
|
|
if executor is not None:
|
||
|
|
executor._shutdown_thread = True
|
||
|
|
# Cancel pending work items if requested.
|
||
|
|
if executor._cancel_pending_futures:
|
||
|
|
# Cancel all pending futures and update pending_work_items
|
||
|
|
# to only have futures that are currently running.
|
||
|
|
new_pending_work_items = {}
|
||
|
|
for work_id, work_item in self.pending_work_items.items():
|
||
|
|
if not work_item.future.cancel():
|
||
|
|
new_pending_work_items[work_id] = work_item
|
||
|
|
self.pending_work_items = new_pending_work_items
|
||
|
|
# Drain work_ids_queue since we no longer need to
|
||
|
|
# add items to the call queue.
|
||
|
|
while True:
|
||
|
|
try:
|
||
|
|
self.work_ids_queue.get_nowait()
|
||
|
|
except queue.Empty:
|
||
|
|
break
|
||
|
|
# Make sure we do this only once to not waste time looping
|
||
|
|
# on running processes over and over.
|
||
|
|
executor._cancel_pending_futures = False
|
||
|
|
|
||
|
|
def shutdown_workers(self):
|
||
|
|
n_children_to_stop = self.get_n_children_alive()
|
||
|
|
n_sentinels_sent = 0
|
||
|
|
# Send the right number of sentinels, to make sure all children are
|
||
|
|
# properly terminated.
|
||
|
|
while (n_sentinels_sent < n_children_to_stop
|
||
|
|
and self.get_n_children_alive() > 0):
|
||
|
|
for i in range(n_children_to_stop - n_sentinels_sent):
|
||
|
|
try:
|
||
|
|
self.call_queue.put_nowait(None)
|
||
|
|
n_sentinels_sent += 1
|
||
|
|
except queue.Full:
|
||
|
|
break
|
||
|
|
|
||
|
|
def join_executor_internals(self):
|
||
|
|
self.shutdown_workers()
|
||
|
|
# Release the queue's resources as soon as possible.
|
||
|
|
self.call_queue.close()
|
||
|
|
self.call_queue.join_thread()
|
||
|
|
with self.shutdown_lock:
|
||
|
|
self.thread_wakeup.close()
|
||
|
|
# If .join() is not called on the created processes then
|
||
|
|
# some ctx.Queue methods may deadlock on Mac OS X.
|
||
|
|
for p in self.processes.values():
|
||
|
|
p.join()
|
||
|
|
|
||
|
|
def get_n_children_alive(self):
|
||
|
|
# This is an upper bound on the number of children alive.
|
||
|
|
return sum(p.is_alive() for p in self.processes.values())
|
||
|
|
|
||
|
|
|
||
|
|
_system_limits_checked = False
|
||
|
|
_system_limited = None
|
||
|
|
|
||
|
|
|
||
|
|
def _check_system_limits():
|
||
|
|
global _system_limits_checked, _system_limited
|
||
|
|
if _system_limits_checked:
|
||
|
|
if _system_limited:
|
||
|
|
raise NotImplementedError(_system_limited)
|
||
|
|
_system_limits_checked = True
|
||
|
|
try:
|
||
|
|
import multiprocessing.synchronize
|
||
|
|
except ImportError:
|
||
|
|
_system_limited = (
|
||
|
|
"This Python build lacks multiprocessing.synchronize, usually due "
|
||
|
|
"to named semaphores being unavailable on this platform."
|
||
|
|
)
|
||
|
|
raise NotImplementedError(_system_limited)
|
||
|
|
try:
|
||
|
|
nsems_max = os.sysconf("SC_SEM_NSEMS_MAX")
|
||
|
|
except (AttributeError, ValueError):
|
||
|
|
# sysconf not available or setting not available
|
||
|
|
return
|
||
|
|
if nsems_max == -1:
|
||
|
|
# indetermined limit, assume that limit is determined
|
||
|
|
# by available memory only
|
||
|
|
return
|
||
|
|
if nsems_max >= 256:
|
||
|
|
# minimum number of semaphores available
|
||
|
|
# according to POSIX
|
||
|
|
return
|
||
|
|
_system_limited = ("system provides too few semaphores (%d"
|
||
|
|
" available, 256 necessary)" % nsems_max)
|
||
|
|
raise NotImplementedError(_system_limited)
|
||
|
|
|
||
|
|
|
||
|
|
def _chain_from_iterable_of_lists(iterable):
|
||
|
|
"""
|
||
|
|
Specialized implementation of itertools.chain.from_iterable.
|
||
|
|
Each item in *iterable* should be a list. This function is
|
||
|
|
careful not to keep references to yielded objects.
|
||
|
|
"""
|
||
|
|
for element in iterable:
|
||
|
|
element.reverse()
|
||
|
|
while element:
|
||
|
|
yield element.pop()
|
||
|
|
|
||
|
|
|
||
|
|
class BrokenProcessPool(_base.BrokenExecutor):
|
||
|
|
"""
|
||
|
|
Raised when a process in a ProcessPoolExecutor terminated abruptly
|
||
|
|
while a future was in the running state.
|
||
|
|
"""
|
||
|
|
|
||
|
|
|
||
|
|
class ProcessPoolExecutor(_base.Executor):
|
||
|
|
def __init__(self, max_workers=None, mp_context=None,
|
||
|
|
initializer=None, initargs=()):
|
||
|
|
"""Initializes a new ProcessPoolExecutor instance.
|
||
|
|
|
||
|
|
Args:
|
||
|
|
max_workers: The maximum number of processes that can be used to
|
||
|
|
execute the given calls. If None or not given then as many
|
||
|
|
worker processes will be created as the machine has processors.
|
||
|
|
mp_context: A multiprocessing context to launch the workers. This
|
||
|
|
object should provide SimpleQueue, Queue and Process.
|
||
|
|
initializer: A callable used to initialize worker processes.
|
||
|
|
initargs: A tuple of arguments to pass to the initializer.
|
||
|
|
"""
|
||
|
|
_check_system_limits()
|
||
|
|
|
||
|
|
if max_workers is None:
|
||
|
|
self._max_workers = os.cpu_count() or 1
|
||
|
|
if sys.platform == 'win32':
|
||
|
|
self._max_workers = min(_MAX_WINDOWS_WORKERS,
|
||
|
|
self._max_workers)
|
||
|
|
else:
|
||
|
|
if max_workers <= 0:
|
||
|
|
raise ValueError("max_workers must be greater than 0")
|
||
|
|
elif (sys.platform == 'win32' and
|
||
|
|
max_workers > _MAX_WINDOWS_WORKERS):
|
||
|
|
raise ValueError(
|
||
|
|
f"max_workers must be <= {_MAX_WINDOWS_WORKERS}")
|
||
|
|
|
||
|
|
self._max_workers = max_workers
|
||
|
|
|
||
|
|
if mp_context is None:
|
||
|
|
mp_context = mp.get_context()
|
||
|
|
self._mp_context = mp_context
|
||
|
|
|
||
|
|
# https://github.com/python/cpython/issues/90622
|
||
|
|
self._safe_to_dynamically_spawn_children = (
|
||
|
|
self._mp_context.get_start_method(allow_none=False) != "fork")
|
||
|
|
|
||
|
|
if initializer is not None and not callable(initializer):
|
||
|
|
raise TypeError("initializer must be a callable")
|
||
|
|
self._initializer = initializer
|
||
|
|
self._initargs = initargs
|
||
|
|
|
||
|
|
# Management thread
|
||
|
|
self._executor_manager_thread = None
|
||
|
|
|
||
|
|
# Map of pids to processes
|
||
|
|
self._processes = {}
|
||
|
|
|
||
|
|
# Shutdown is a two-step process.
|
||
|
|
self._shutdown_thread = False
|
||
|
|
self._shutdown_lock = threading.Lock()
|
||
|
|
self._idle_worker_semaphore = threading.Semaphore(0)
|
||
|
|
self._broken = False
|
||
|
|
self._queue_count = 0
|
||
|
|
self._pending_work_items = {}
|
||
|
|
self._cancel_pending_futures = False
|
||
|
|
|
||
|
|
# _ThreadWakeup is a communication channel used to interrupt the wait
|
||
|
|
# of the main loop of executor_manager_thread from another thread (e.g.
|
||
|
|
# when calling executor.submit or executor.shutdown). We do not use the
|
||
|
|
# _result_queue to send wakeup signals to the executor_manager_thread
|
||
|
|
# as it could result in a deadlock if a worker process dies with the
|
||
|
|
# _result_queue write lock still acquired.
|
||
|
|
#
|
||
|
|
# _shutdown_lock must be locked to access _ThreadWakeup.
|
||
|
|
self._executor_manager_thread_wakeup = _ThreadWakeup()
|
||
|
|
|
||
|
|
# Create communication channels for the executor
|
||
|
|
# Make the call queue slightly larger than the number of processes to
|
||
|
|
# prevent the worker processes from idling. But don't make it too big
|
||
|
|
# because futures in the call queue cannot be cancelled.
|
||
|
|
queue_size = self._max_workers + EXTRA_QUEUED_CALLS
|
||
|
|
self._call_queue = _SafeQueue(
|
||
|
|
max_size=queue_size, ctx=self._mp_context,
|
||
|
|
pending_work_items=self._pending_work_items,
|
||
|
|
shutdown_lock=self._shutdown_lock,
|
||
|
|
thread_wakeup=self._executor_manager_thread_wakeup)
|
||
|
|
# Killed worker processes can produce spurious "broken pipe"
|
||
|
|
# tracebacks in the queue's own worker thread. But we detect killed
|
||
|
|
# processes anyway, so silence the tracebacks.
|
||
|
|
self._call_queue._ignore_epipe = True
|
||
|
|
self._result_queue = mp_context.SimpleQueue()
|
||
|
|
self._work_ids = queue.Queue()
|
||
|
|
|
||
|
|
def _start_executor_manager_thread(self):
|
||
|
|
if self._executor_manager_thread is None:
|
||
|
|
# Start the processes so that their sentinels are known.
|
||
|
|
if not self._safe_to_dynamically_spawn_children: # ie, using fork.
|
||
|
|
self._launch_processes()
|
||
|
|
self._executor_manager_thread = _ExecutorManagerThread(self)
|
||
|
|
self._executor_manager_thread.start()
|
||
|
|
_threads_wakeups[self._executor_manager_thread] = \
|
||
|
|
self._executor_manager_thread_wakeup
|
||
|
|
|
||
|
|
def _adjust_process_count(self):
|
||
|
|
# if there's an idle process, we don't need to spawn a new one.
|
||
|
|
if self._idle_worker_semaphore.acquire(blocking=False):
|
||
|
|
return
|
||
|
|
|
||
|
|
process_count = len(self._processes)
|
||
|
|
if process_count < self._max_workers:
|
||
|
|
# Assertion disabled as this codepath is also used to replace a
|
||
|
|
# worker that unexpectedly dies, even when using the 'fork' start
|
||
|
|
# method. That means there is still a potential deadlock bug. If a
|
||
|
|
# 'fork' mp_context worker dies, we'll be forking a new one when
|
||
|
|
# we know a thread is running (self._executor_manager_thread).
|
||
|
|
#assert self._safe_to_dynamically_spawn_children or not self._executor_manager_thread, 'https://github.com/python/cpython/issues/90622'
|
||
|
|
self._spawn_process()
|
||
|
|
|
||
|
|
def _launch_processes(self):
|
||
|
|
# https://github.com/python/cpython/issues/90622
|
||
|
|
assert not self._executor_manager_thread, (
|
||
|
|
'Processes cannot be fork()ed after the thread has started, '
|
||
|
|
'deadlock in the child processes could result.')
|
||
|
|
for _ in range(len(self._processes), self._max_workers):
|
||
|
|
self._spawn_process()
|
||
|
|
|
||
|
|
def _spawn_process(self):
|
||
|
|
p = self._mp_context.Process(
|
||
|
|
target=_process_worker,
|
||
|
|
args=(self._call_queue,
|
||
|
|
self._result_queue,
|
||
|
|
self._initializer,
|
||
|
|
self._initargs))
|
||
|
|
p.start()
|
||
|
|
self._processes[p.pid] = p
|
||
|
|
|
||
|
|
def submit(self, fn, /, *args, **kwargs):
|
||
|
|
with self._shutdown_lock:
|
||
|
|
if self._broken:
|
||
|
|
raise BrokenProcessPool(self._broken)
|
||
|
|
if self._shutdown_thread:
|
||
|
|
raise RuntimeError('cannot schedule new futures after shutdown')
|
||
|
|
if _global_shutdown:
|
||
|
|
raise RuntimeError('cannot schedule new futures after '
|
||
|
|
'interpreter shutdown')
|
||
|
|
|
||
|
|
f = _base.Future()
|
||
|
|
w = _WorkItem(f, fn, args, kwargs)
|
||
|
|
|
||
|
|
self._pending_work_items[self._queue_count] = w
|
||
|
|
self._work_ids.put(self._queue_count)
|
||
|
|
self._queue_count += 1
|
||
|
|
# Wake up queue management thread
|
||
|
|
self._executor_manager_thread_wakeup.wakeup()
|
||
|
|
|
||
|
|
if self._safe_to_dynamically_spawn_children:
|
||
|
|
self._adjust_process_count()
|
||
|
|
self._start_executor_manager_thread()
|
||
|
|
return f
|
||
|
|
submit.__doc__ = _base.Executor.submit.__doc__
|
||
|
|
|
||
|
|
def map(self, fn, *iterables, timeout=None, chunksize=1):
|
||
|
|
"""Returns an iterator equivalent to map(fn, iter).
|
||
|
|
|
||
|
|
Args:
|
||
|
|
fn: A callable that will take as many arguments as there are
|
||
|
|
passed iterables.
|
||
|
|
timeout: The maximum number of seconds to wait. If None, then there
|
||
|
|
is no limit on the wait time.
|
||
|
|
chunksize: If greater than one, the iterables will be chopped into
|
||
|
|
chunks of size chunksize and submitted to the process pool.
|
||
|
|
If set to one, the items in the list will be sent one at a time.
|
||
|
|
|
||
|
|
Returns:
|
||
|
|
An iterator equivalent to: map(func, *iterables) but the calls may
|
||
|
|
be evaluated out-of-order.
|
||
|
|
|
||
|
|
Raises:
|
||
|
|
TimeoutError: If the entire result iterator could not be generated
|
||
|
|
before the given timeout.
|
||
|
|
Exception: If fn(*args) raises for any values.
|
||
|
|
"""
|
||
|
|
if chunksize < 1:
|
||
|
|
raise ValueError("chunksize must be >= 1.")
|
||
|
|
|
||
|
|
results = super().map(partial(_process_chunk, fn),
|
||
|
|
_get_chunks(*iterables, chunksize=chunksize),
|
||
|
|
timeout=timeout)
|
||
|
|
return _chain_from_iterable_of_lists(results)
|
||
|
|
|
||
|
|
def shutdown(self, wait=True, *, cancel_futures=False):
|
||
|
|
with self._shutdown_lock:
|
||
|
|
self._cancel_pending_futures = cancel_futures
|
||
|
|
self._shutdown_thread = True
|
||
|
|
if self._executor_manager_thread_wakeup is not None:
|
||
|
|
# Wake up queue management thread
|
||
|
|
self._executor_manager_thread_wakeup.wakeup()
|
||
|
|
|
||
|
|
if self._executor_manager_thread is not None and wait:
|
||
|
|
self._executor_manager_thread.join()
|
||
|
|
# To reduce the risk of opening too many files, remove references to
|
||
|
|
# objects that use file descriptors.
|
||
|
|
self._executor_manager_thread = None
|
||
|
|
self._call_queue = None
|
||
|
|
if self._result_queue is not None and wait:
|
||
|
|
self._result_queue.close()
|
||
|
|
self._result_queue = None
|
||
|
|
self._processes = None
|
||
|
|
self._executor_manager_thread_wakeup = None
|
||
|
|
|
||
|
|
shutdown.__doc__ = _base.Executor.shutdown.__doc__
|