diff options
| -rw-r--r-- | Lib/multiprocessing/pool.py | 112 | ||||
| -rw-r--r-- | Lib/test/_test_multiprocessing.py | 1 | ||||
| -rw-r--r-- | Misc/NEWS.d/next/Library/2019-01-21-02-15-20.bpo-35378.4oF03i.rst | 6 |
3 files changed, 80 insertions, 39 deletions
diff --git a/Lib/multiprocessing/pool.py b/Lib/multiprocessing/pool.py index bfb2769..18a56f8 100644 --- a/Lib/multiprocessing/pool.py +++ b/Lib/multiprocessing/pool.py @@ -151,8 +151,9 @@ class Pool(object): ''' _wrap_exception = True - def Process(self, *args, **kwds): - return self._ctx.Process(*args, **kwds) + @staticmethod + def Process(ctx, *args, **kwds): + return ctx.Process(*args, **kwds) def __init__(self, processes=None, initializer=None, initargs=(), maxtasksperchild=None, context=None): @@ -190,7 +191,10 @@ class Pool(object): self._worker_handler = threading.Thread( target=Pool._handle_workers, - args=(self, ) + args=(self._cache, self._taskqueue, self._ctx, self.Process, + self._processes, self._pool, self._inqueue, self._outqueue, + self._initializer, self._initargs, self._maxtasksperchild, + self._wrap_exception) ) self._worker_handler.daemon = True self._worker_handler._state = RUN @@ -236,43 +240,61 @@ class Pool(object): f'state={self._state} ' f'pool_size={len(self._pool)}>') - def _join_exited_workers(self): + @staticmethod + def _join_exited_workers(pool): """Cleanup after any worker processes which have exited due to reaching their specified lifetime. Returns True if any workers were cleaned up. """ cleaned = False - for i in reversed(range(len(self._pool))): - worker = self._pool[i] + for i in reversed(range(len(pool))): + worker = pool[i] if worker.exitcode is not None: # worker exited util.debug('cleaning up worker %d' % i) worker.join() cleaned = True - del self._pool[i] + del pool[i] return cleaned def _repopulate_pool(self): + return self._repopulate_pool_static(self._ctx, self.Process, + self._processes, + self._pool, self._inqueue, + self._outqueue, self._initializer, + self._initargs, + self._maxtasksperchild, + self._wrap_exception) + + @staticmethod + def _repopulate_pool_static(ctx, Process, processes, pool, inqueue, + outqueue, initializer, initargs, + maxtasksperchild, wrap_exception): """Bring the number of pool processes up to the specified number, for use after reaping workers which have exited. """ - for i in range(self._processes - len(self._pool)): - w = self.Process(target=worker, - args=(self._inqueue, self._outqueue, - self._initializer, - self._initargs, self._maxtasksperchild, - self._wrap_exception) - ) + for i in range(processes - len(pool)): + w = Process(ctx, target=worker, + args=(inqueue, outqueue, + initializer, + initargs, maxtasksperchild, + wrap_exception)) w.name = w.name.replace('Process', 'PoolWorker') w.daemon = True w.start() - self._pool.append(w) + pool.append(w) util.debug('added worker') - def _maintain_pool(self): + @staticmethod + def _maintain_pool(ctx, Process, processes, pool, inqueue, outqueue, + initializer, initargs, maxtasksperchild, + wrap_exception): """Clean up any exited workers and start replacements for them. """ - if self._join_exited_workers(): - self._repopulate_pool() + if Pool._join_exited_workers(pool): + Pool._repopulate_pool_static(ctx, Process, processes, pool, + inqueue, outqueue, initializer, + initargs, maxtasksperchild, + wrap_exception) def _setup_queues(self): self._inqueue = self._ctx.SimpleQueue() @@ -331,7 +353,7 @@ class Pool(object): ''' self._check_running() if chunksize == 1: - result = IMapIterator(self._cache) + result = IMapIterator(self) self._taskqueue.put( ( self._guarded_task_generation(result._job, func, iterable), @@ -344,7 +366,7 @@ class Pool(object): "Chunksize must be 1+, not {0:n}".format( chunksize)) task_batches = Pool._get_tasks(func, iterable, chunksize) - result = IMapIterator(self._cache) + result = IMapIterator(self) self._taskqueue.put( ( self._guarded_task_generation(result._job, @@ -360,7 +382,7 @@ class Pool(object): ''' self._check_running() if chunksize == 1: - result = IMapUnorderedIterator(self._cache) + result = IMapUnorderedIterator(self) self._taskqueue.put( ( self._guarded_task_generation(result._job, func, iterable), @@ -372,7 +394,7 @@ class Pool(object): raise ValueError( "Chunksize must be 1+, not {0!r}".format(chunksize)) task_batches = Pool._get_tasks(func, iterable, chunksize) - result = IMapUnorderedIterator(self._cache) + result = IMapUnorderedIterator(self) self._taskqueue.put( ( self._guarded_task_generation(result._job, @@ -388,7 +410,7 @@ class Pool(object): Asynchronous version of `apply()` method. ''' self._check_running() - result = ApplyResult(self._cache, callback, error_callback) + result = ApplyResult(self, callback, error_callback) self._taskqueue.put(([(result._job, 0, func, args, kwds)], None)) return result @@ -417,7 +439,7 @@ class Pool(object): chunksize = 0 task_batches = Pool._get_tasks(func, iterable, chunksize) - result = MapResult(self._cache, chunksize, len(iterable), callback, + result = MapResult(self, chunksize, len(iterable), callback, error_callback=error_callback) self._taskqueue.put( ( @@ -430,16 +452,20 @@ class Pool(object): return result @staticmethod - def _handle_workers(pool): + def _handle_workers(cache, taskqueue, ctx, Process, processes, pool, + inqueue, outqueue, initializer, initargs, + maxtasksperchild, wrap_exception): thread = threading.current_thread() # Keep maintaining workers until the cache gets drained, unless the pool # is terminated. - while thread._state == RUN or (pool._cache and thread._state != TERMINATE): - pool._maintain_pool() + while thread._state == RUN or (cache and thread._state != TERMINATE): + Pool._maintain_pool(ctx, Process, processes, pool, inqueue, + outqueue, initializer, initargs, + maxtasksperchild, wrap_exception) time.sleep(0.1) # send sentinel to stop workers - pool._taskqueue.put(None) + taskqueue.put(None) util.debug('worker handler exiting') @staticmethod @@ -656,13 +682,14 @@ class Pool(object): class ApplyResult(object): - def __init__(self, cache, callback, error_callback): + def __init__(self, pool, callback, error_callback): + self._pool = pool self._event = threading.Event() self._job = next(job_counter) - self._cache = cache + self._cache = pool._cache self._callback = callback self._error_callback = error_callback - cache[self._job] = self + self._cache[self._job] = self def ready(self): return self._event.is_set() @@ -692,6 +719,7 @@ class ApplyResult(object): self._error_callback(self._value) self._event.set() del self._cache[self._job] + self._pool = None AsyncResult = ApplyResult # create alias -- see #17805 @@ -701,8 +729,8 @@ AsyncResult = ApplyResult # create alias -- see #17805 class MapResult(ApplyResult): - def __init__(self, cache, chunksize, length, callback, error_callback): - ApplyResult.__init__(self, cache, callback, + def __init__(self, pool, chunksize, length, callback, error_callback): + ApplyResult.__init__(self, pool, callback, error_callback=error_callback) self._success = True self._value = [None] * length @@ -710,7 +738,7 @@ class MapResult(ApplyResult): if chunksize <= 0: self._number_left = 0 self._event.set() - del cache[self._job] + del self._cache[self._job] else: self._number_left = length//chunksize + bool(length % chunksize) @@ -724,6 +752,7 @@ class MapResult(ApplyResult): self._callback(self._value) del self._cache[self._job] self._event.set() + self._pool = None else: if not success and self._success: # only store first exception @@ -735,6 +764,7 @@ class MapResult(ApplyResult): self._error_callback(self._value) del self._cache[self._job] self._event.set() + self._pool = None # # Class whose instances are returned by `Pool.imap()` @@ -742,15 +772,16 @@ class MapResult(ApplyResult): class IMapIterator(object): - def __init__(self, cache): + def __init__(self, pool): + self._pool = pool self._cond = threading.Condition(threading.Lock()) self._job = next(job_counter) - self._cache = cache + self._cache = pool._cache self._items = collections.deque() self._index = 0 self._length = None self._unsorted = {} - cache[self._job] = self + self._cache[self._job] = self def __iter__(self): return self @@ -761,12 +792,14 @@ class IMapIterator(object): item = self._items.popleft() except IndexError: if self._index == self._length: + self._pool = None raise StopIteration from None self._cond.wait(timeout) try: item = self._items.popleft() except IndexError: if self._index == self._length: + self._pool = None raise StopIteration from None raise TimeoutError from None @@ -792,6 +825,7 @@ class IMapIterator(object): if self._index == self._length: del self._cache[self._job] + self._pool = None def _set_length(self, length): with self._cond: @@ -799,6 +833,7 @@ class IMapIterator(object): if self._index == self._length: self._cond.notify() del self._cache[self._job] + self._pool = None # # Class whose instances are returned by `Pool.imap_unordered()` @@ -813,6 +848,7 @@ class IMapUnorderedIterator(IMapIterator): self._cond.notify() if self._index == self._length: del self._cache[self._job] + self._pool = None # # @@ -822,7 +858,7 @@ class ThreadPool(Pool): _wrap_exception = False @staticmethod - def Process(*args, **kwds): + def Process(ctx, *args, **kwds): from .dummy import Process return Process(*args, **kwds) diff --git a/Lib/test/_test_multiprocessing.py b/Lib/test/_test_multiprocessing.py index bc1072d..d93303b 100644 --- a/Lib/test/_test_multiprocessing.py +++ b/Lib/test/_test_multiprocessing.py @@ -2593,7 +2593,6 @@ class _TestPool(BaseTestCase): pool = None support.gc_collect() - def raising(): raise KeyError("key") diff --git a/Misc/NEWS.d/next/Library/2019-01-21-02-15-20.bpo-35378.4oF03i.rst b/Misc/NEWS.d/next/Library/2019-01-21-02-15-20.bpo-35378.4oF03i.rst new file mode 100644 index 0000000..bb57f71 --- /dev/null +++ b/Misc/NEWS.d/next/Library/2019-01-21-02-15-20.bpo-35378.4oF03i.rst @@ -0,0 +1,6 @@ +Fix a reference issue inside :class:`multiprocessing.Pool` that caused +the pool to remain alive if it was deleted without being closed or +terminated explicitly. A new strong reference is added to the pool +iterators to link the lifetime of the pool to the lifetime of its +iterators so the pool does not get destroyed if a pool iterator is +still alive. |