90ca184486
## What changes were proposed in this pull request? Currently, Broaccast.unpersist() will remove the file of broadcast, which should be the behavior of destroy(). This PR added destroy() for Broadcast in Python, to match the sematics in Scala. ## How was this patch tested? Added regression tests. Author: Davies Liu <davies@databricks.com> Closes #12189 from davies/py_unpersist.
136 lines
4.2 KiB
Python
136 lines
4.2 KiB
Python
#
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# Licensed to the Apache Software Foundation (ASF) under one or more
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# contributor license agreements. See the NOTICE file distributed with
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# this work for additional information regarding copyright ownership.
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# The ASF licenses this file to You under the Apache License, Version 2.0
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# (the "License"); you may not use this file except in compliance with
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# the License. You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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#
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import os
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import sys
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import gc
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from tempfile import NamedTemporaryFile
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if sys.version < '3':
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import cPickle as pickle
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else:
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import pickle
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unicode = str
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__all__ = ['Broadcast']
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# Holds broadcasted data received from Java, keyed by its id.
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_broadcastRegistry = {}
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def _from_id(bid):
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from pyspark.broadcast import _broadcastRegistry
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if bid not in _broadcastRegistry:
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raise Exception("Broadcast variable '%s' not loaded!" % bid)
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return _broadcastRegistry[bid]
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class Broadcast(object):
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"""
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A broadcast variable created with L{SparkContext.broadcast()}.
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Access its value through C{.value}.
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Examples:
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>>> from pyspark.context import SparkContext
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>>> sc = SparkContext('local', 'test')
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>>> b = sc.broadcast([1, 2, 3, 4, 5])
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>>> b.value
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[1, 2, 3, 4, 5]
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>>> sc.parallelize([0, 0]).flatMap(lambda x: b.value).collect()
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[1, 2, 3, 4, 5, 1, 2, 3, 4, 5]
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>>> b.unpersist()
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>>> large_broadcast = sc.broadcast(range(10000))
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"""
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def __init__(self, sc=None, value=None, pickle_registry=None, path=None):
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"""
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Should not be called directly by users -- use L{SparkContext.broadcast()}
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instead.
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"""
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if sc is not None:
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f = NamedTemporaryFile(delete=False, dir=sc._temp_dir)
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self._path = self.dump(value, f)
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self._jbroadcast = sc._jvm.PythonRDD.readBroadcastFromFile(sc._jsc, self._path)
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self._pickle_registry = pickle_registry
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else:
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self._jbroadcast = None
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self._path = path
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def dump(self, value, f):
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pickle.dump(value, f, 2)
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f.close()
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return f.name
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def load(self, path):
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with open(path, 'rb', 1 << 20) as f:
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# pickle.load() may create lots of objects, disable GC
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# temporary for better performance
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gc.disable()
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try:
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return pickle.load(f)
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finally:
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gc.enable()
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@property
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def value(self):
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""" Return the broadcasted value
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"""
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if not hasattr(self, "_value") and self._path is not None:
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self._value = self.load(self._path)
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return self._value
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def unpersist(self, blocking=False):
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"""
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Delete cached copies of this broadcast on the executors. If the
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broadcast is used after this is called, it will need to be
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re-sent to each executor.
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:param blocking: Whether to block until unpersisting has completed
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"""
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if self._jbroadcast is None:
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raise Exception("Broadcast can only be unpersisted in driver")
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self._jbroadcast.unpersist(blocking)
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def destroy(self):
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"""
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Destroy all data and metadata related to this broadcast variable.
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Use this with caution; once a broadcast variable has been destroyed,
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it cannot be used again. This method blocks until destroy has
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completed.
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"""
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if self._jbroadcast is None:
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raise Exception("Broadcast can only be destroyed in driver")
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self._jbroadcast.destroy()
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os.unlink(self._path)
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def __reduce__(self):
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if self._jbroadcast is None:
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raise Exception("Broadcast can only be serialized in driver")
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self._pickle_registry.add(self)
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return _from_id, (self._jbroadcast.id(),)
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if __name__ == "__main__":
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import doctest
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(failure_count, test_count) = doctest.testmod()
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if failure_count:
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exit(-1)
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