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#
# Licensed to the Apache Software Foundation (ASF) under one or more
# contributor license agreements. See the NOTICE file distributed with
# this work for additional information regarding copyright ownership.
# The ASF licenses this file to You 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.
#
"""
>>> from pyspark.context import SparkContext
>>> sc = SparkContext('local', 'test')
>>> b = sc.broadcast([1, 2, 3, 4, 5])
>>> b.value
[1, 2, 3, 4, 5]
>>> sc.parallelize([0, 0]).flatMap(lambda x: b.value).collect()
[1, 2, 3, 4, 5, 1, 2, 3, 4, 5]
>>> b.unpersist()
>>> large_broadcast = sc.broadcast(list(range(10000)))
"""
import os
from pyspark.serializers import CompressedSerializer, PickleSerializer
__all__ = ['Broadcast']
# Holds broadcasted data received from Java, keyed by its id.
_broadcastRegistry = {}
def _from_id(bid):
from pyspark.broadcast import _broadcastRegistry
if bid not in _broadcastRegistry:
raise Exception("Broadcast variable '%s' not loaded!" % bid)
return _broadcastRegistry[bid]
class Broadcast(object):
"""
A broadcast variable created with
L{SparkContext.broadcast()<pyspark.context.SparkContext.broadcast>}.
Access its value through C{.value}.
"""
def __init__(self, bid, value, java_broadcast=None,
pickle_registry=None, path=None):
"""
Should not be called directly by users -- use
L{SparkContext.broadcast()<pyspark.context.SparkContext.broadcast>}
instead.
"""
self.bid = bid
if path is None:
self._value = value
self._jbroadcast = java_broadcast
self._pickle_registry = pickle_registry
self.path = path
@property
def value(self):
""" Return the broadcasted value
"""
if not hasattr(self, "_value") and self.path is not None:
ser = CompressedSerializer(PickleSerializer())
self._value = ser.load_stream(open(self.path)).next()
return self._value
def unpersist(self, blocking=False):
"""
Delete cached copies of this broadcast on the executors.
"""
self._jbroadcast.unpersist(blocking)
os.unlink(self.path)
def __reduce__(self):
self._pickle_registry.add(self)
return (_from_id, (self.bid, ))
if __name__ == "__main__":
import doctest
doctest.testmod()
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