Source code for pyspark.broadcast

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import gc
import os
import sys
from tempfile import NamedTemporaryFile
import threading
import pickle

from pyspark.java_gateway import local_connect_and_auth
from pyspark.serializers import ChunkedStream, pickle_protocol
from pyspark.util import print_exec

__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 RuntimeError("Broadcast variable '%s' not loaded!" % bid)
    return _broadcastRegistry[bid]

[docs]class Broadcast(object): """ A broadcast variable created with :meth:`SparkContext.broadcast`. Access its value through :attr:`value`. Examples -------- >>> 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(range(10000)) """ def __init__(self, sc=None, value=None, pickle_registry=None, path=None, sock_file=None): """ Should not be called directly by users -- use :meth:`SparkContext.broadcast` instead. """ if sc is not None: # we're on the driver. We want the pickled data to end up in a file (maybe encrypted) f = NamedTemporaryFile(delete=False, dir=sc._temp_dir) self._path = self._sc = sc self._python_broadcast = sc._jvm.PythonRDD.setupBroadcast(self._path) if sc._encryption_enabled: # with encryption, we ask the jvm to do the encryption for us, we send it data # over a socket port, auth_secret = self._python_broadcast.setupEncryptionServer() (encryption_sock_file, _) = local_connect_and_auth(port, auth_secret) broadcast_out = ChunkedStream(encryption_sock_file, 8192) else: # no encryption, we can just write pickled data directly to the file from python broadcast_out = f self.dump(value, broadcast_out) if sc._encryption_enabled: self._python_broadcast.waitTillDataReceived() self._jbroadcast = sc._jsc.broadcast(self._python_broadcast) self._pickle_registry = pickle_registry else: # we're on an executor self._jbroadcast = None self._sc = None self._python_broadcast = None if sock_file is not None: # the jvm is doing decryption for us. Read the value # immediately from the sock_file self._value = self.load(sock_file) else: # the jvm just dumps the pickled data in path -- we'll unpickle lazily when # the value is requested assert(path is not None) self._path = path
[docs] def dump(self, value, f): try: pickle.dump(value, f, pickle_protocol) except pickle.PickleError: raise except Exception as e: msg = "Could not serialize broadcast: %s: %s" \ % (e.__class__.__name__, str(e)) print_exec(sys.stderr) raise pickle.PicklingError(msg) f.close()
[docs] def load_from_path(self, path): with open(path, 'rb', 1 << 20) as f: return self.load(f)
[docs] def load(self, file): # "file" could also be a socket gc.disable() try: return pickle.load(file) finally: gc.enable()
@property def value(self): """ Return the broadcasted value """ if not hasattr(self, "_value") and self._path is not None: # we only need to decrypt it here when encryption is enabled and # if its on the driver, since executor decryption is handled already if self._sc is not None and self._sc._encryption_enabled: port, auth_secret = self._python_broadcast.setupDecryptionServer() (decrypted_sock_file, _) = local_connect_and_auth(port, auth_secret) self._python_broadcast.waitTillBroadcastDataSent() return self.load(decrypted_sock_file) else: self._value = self.load_from_path(self._path) return self._value
[docs] def unpersist(self, blocking=False): """ Delete cached copies of this broadcast on the executors. If the broadcast is used after this is called, it will need to be re-sent to each executor. Parameters ---------- blocking : bool, optional Whether to block until unpersisting has completed """ if self._jbroadcast is None: raise RuntimeError("Broadcast can only be unpersisted in driver") self._jbroadcast.unpersist(blocking)
[docs] def destroy(self, blocking=False): """ Destroy all data and metadata related to this broadcast variable. Use this with caution; once a broadcast variable has been destroyed, it cannot be used again. .. versionchanged:: 3.0.0 Added optional argument `blocking` to specify whether to block until all blocks are deleted. Parameters ---------- blocking : bool, optional Whether to block until unpersisting has completed """ if self._jbroadcast is None: raise RuntimeError("Broadcast can only be destroyed in driver") self._jbroadcast.destroy(blocking) os.unlink(self._path)
def __reduce__(self): if self._jbroadcast is None: raise RuntimeError("Broadcast can only be serialized in driver") self._pickle_registry.add(self) return _from_id, (,)
class BroadcastPickleRegistry(threading.local): """ Thread-local registry for broadcast variables that have been pickled """ def __init__(self): self.__dict__.setdefault("_registry", set()) def __iter__(self): for bcast in self._registry: yield bcast def add(self, bcast): self._registry.add(bcast) def clear(self): self._registry.clear() if __name__ == "__main__": import doctest (failure_count, test_count) = doctest.testmod() if failure_count: sys.exit(-1)