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e121667 Dec 30, 2016
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# Copyright 2015 The TensorFlow Authors. All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
# ==============================================================================
"""Contains a helper context for running queue runners.
@@NestedQueueRunnerError
@@QueueRunners
"""
from __future__ import absolute_import
from __future__ import division
from __future__ import print_function
from contextlib import contextmanager
import threading
from tensorflow.python.framework import ops
from tensorflow.python.training import coordinator
__all__ = [
'NestedQueueRunnerError',
'QueueRunners',
]
_queue_runner_lock = threading.Lock()
class NestedQueueRunnerError(Exception):
pass
@contextmanager
def QueueRunners(session):
"""Creates a context manager that handles starting and stopping queue runners.
Args:
session: the currently running session.
Yields:
a context in which queues are run.
Raises:
NestedQueueRunnerError: if a QueueRunners context is nested within another.
"""
if not _queue_runner_lock.acquire(False):
raise NestedQueueRunnerError('QueueRunners cannot be nested')
coord = coordinator.Coordinator()
threads = []
for qr in ops.get_collection(ops.GraphKeys.QUEUE_RUNNERS):
threads.extend(
qr.create_threads(
session, coord=coord, daemon=True, start=True))
try:
yield
finally:
coord.request_stop()
coord.join(threads, stop_grace_period_secs=120)
_queue_runner_lock.release()