f971d6cb60
So I finally resurrected this PR. It seems the old one against the incubator mirror is no longer available, so I cannot reference it. This adds initial support for reading Hadoop ```SequenceFile```s, as well as arbitrary Hadoop ```InputFormat```s, in PySpark. # Overview The basics are as follows: 1. ```PythonRDD``` object contains the relevant methods, that are in turn invoked by ```SparkContext``` in PySpark 2. The SequenceFile or InputFormat is read on the Scala side and converted from ```Writable``` instances to the relevant Scala classes (in the case of primitives) 3. Pyrolite is used to serialize Java objects. If this fails, the fallback is ```toString``` 4. ```PickleSerializer``` on the Python side deserializes. This works "out the box" for simple ```Writable```s: * ```Text``` * ```IntWritable```, ```DoubleWritable```, ```FloatWritable``` * ```NullWritable``` * ```BooleanWritable``` * ```BytesWritable``` * ```MapWritable``` It also works for simple, "struct-like" classes. Due to the way Pyrolite works, this requires that the classes satisfy the JavaBeans convenstions (i.e. with fields and a no-arg constructor and getters/setters). (Perhaps in future some sugar for case classes and reflection could be added). I've tested it out with ```ESInputFormat``` as an example and it works very nicely: ```python conf = {"es.resource" : "index/type" } rdd = sc.newAPIHadoopRDD("org.elasticsearch.hadoop.mr.EsInputFormat", "org.apache.hadoop.io.NullWritable", "org.elasticsearch.hadoop.mr.LinkedMapWritable", conf=conf) rdd.first() ``` I suspect for things like HBase/Cassandra it will be a bit trickier to get it to work out the box. # Some things still outstanding: 1. ~~Requires ```msgpack-python``` and will fail without it. As originally discussed with Josh, add a ```as_strings``` argument that defaults to ```False```, that can be used if ```msgpack-python``` is not available~~ 2. ~~I see from https://github.com/apache/spark/pull/363 that Pyrolite is being used there for SerDe between Scala and Python. @ahirreddy @mateiz what is the plan behind this - is Pyrolite preferred? It seems from a cursory glance that adapting the ```msgpack```-based SerDe here to use Pyrolite wouldn't be too hard~~ 3. ~~Support the key and value "wrapper" that would allow a Scala/Java function to be plugged in that would transform whatever the key/value Writable class is into something that can be serialized (e.g. convert some custom Writable to a JavaBean or ```java.util.Map``` that can be easily serialized)~~ 4. Support ```saveAsSequenceFile``` and ```saveAsHadoopFile``` etc. This would require SerDe in the reverse direction, that can be handled by Pyrolite. Will work on this as a separate PR Author: Nick Pentreath <nick.pentreath@gmail.com> Closes #455 from MLnick/pyspark-inputformats and squashes the following commits: 268df7e [Nick Pentreath] Documentation changes mer @pwendell comments 761269b [Nick Pentreath] Address @pwendell comments, simplify default writable conversions and remove registry. 4c972d8 [Nick Pentreath] Add license headers d150431 [Nick Pentreath] Merge remote-tracking branch 'upstream/master' into pyspark-inputformats cde6af9 [Nick Pentreath] Parameterize converter trait 5ebacfa [Nick Pentreath] Update docs for PySpark input formats a985492 [Nick Pentreath] Move Converter examples to own package 365d0be [Nick Pentreath] Make classes private[python]. Add docs and @Experimental annotation to Converter interface. eeb8205 [Nick Pentreath] Fix path relative to SPARK_HOME in tests 1eaa08b [Nick Pentreath] HBase -> Cassandra app name oversight 3f90c3e [Nick Pentreath] Merge remote-tracking branch 'upstream/master' into pyspark-inputformats 2c18513 [Nick Pentreath] Add examples for reading HBase and Cassandra InputFormats from Python b65606f [Nick Pentreath] Add converter interface 5757f6e [Nick Pentreath] Default key/value classes for sequenceFile asre None 085b55f [Nick Pentreath] Move input format tests to tests.py and clean up docs 43eb728 [Nick Pentreath] PySpark InputFormats docs into programming guide 94beedc [Nick Pentreath] Clean up args in PythonRDD. Set key/value converter defaults to None for PySpark context.py methods 1a4a1d6 [Nick Pentreath] Address @mateiz style comments 01e0813 [Nick Pentreath] Merge remote-tracking branch 'upstream/master' into pyspark-inputformats 15a7d07 [Nick Pentreath] Remove default args for key/value classes. Arg names to camelCase 9fe6bd5 [Nick Pentreath] Merge remote-tracking branch 'upstream/master' into pyspark-inputformats 84fe8e3 [Nick Pentreath] Python programming guide space formatting d0f52b6 [Nick Pentreath] Python programming guide 7caa73a [Nick Pentreath] Merge remote-tracking branch 'upstream/master' into pyspark-inputformats 93ef995 [Nick Pentreath] Add back context.py changes 9ef1896 [Nick Pentreath] Recover earlier changes lost in previous merge for serializers.py 077ecb2 [Nick Pentreath] Recover earlier changes lost in previous merge for context.py 5af4770 [Nick Pentreath] Merge branch 'master' into pyspark-inputformats 35b8e3a [Nick Pentreath] Another fix for test ordering bef3afb [Nick Pentreath] Merge remote-tracking branch 'upstream/master' into pyspark-inputformats e001b94 [Nick Pentreath] Fix test failures due to ordering 78978d9 [Nick Pentreath] Add doc for SequenceFile and InputFormat support to Python programming guide 64eb051 [Nick Pentreath] Scalastyle fix e7552fa [Nick Pentreath] Merge branch 'master' into pyspark-inputformats 44f2857 [Nick Pentreath] Remove msgpack dependency and switch serialization to Pyrolite, plus some clean up and refactoring c0ebfb6 [Nick Pentreath] Change sequencefile test data generator to easily be called from PySpark tests 1d7c17c [Nick Pentreath] Amend tests to auto-generate sequencefile data in temp dir 17a656b [Nick Pentreath] remove binary sequencefile for tests f60959e [Nick Pentreath] Remove msgpack dependency and serializer from PySpark 450e0a2 [Nick Pentreath] Merge branch 'master' into pyspark-inputformats 31a2fff [Nick Pentreath] Scalastyle fixes fc5099e [Nick Pentreath] Add Apache license headers 4e08983 [Nick Pentreath] Clean up docs for PySpark context methods b20ec7e [Nick Pentreath] Clean up merge duplicate dependencies 951c117 [Nick Pentreath] Merge branch 'master' into pyspark-inputformats f6aac55 [Nick Pentreath] Bring back msgpack 9d2256e [Nick Pentreath] Merge branch 'master' into pyspark-inputformats 1bbbfb0 [Nick Pentreath] Clean up SparkBuild from merge a67dfad [Nick Pentreath] Clean up Msgpack serialization and registering 7237263 [Nick Pentreath] Add back msgpack serializer and hadoop file code lost during merging 25da1ca [Nick Pentreath] Add generator for nulls, bools, bytes and maps 65360d5 [Nick Pentreath] Adding test SequenceFiles 0c612e5 [Nick Pentreath] Merge branch 'master' into pyspark-inputformats d72bf18 [Nick Pentreath] msgpack dd57922 [Nick Pentreath] Merge remote-tracking branch 'upstream/master' into pyspark-inputformats e67212a [Nick Pentreath] Add back msgpack dependency f2d76a0 [Nick Pentreath] Merge branch 'master' into pyspark-inputformats 41856a5 [Nick Pentreath] Merge branch 'master' into pyspark-inputformats 97ef708 [Nick Pentreath] Remove old writeToStream 2beeedb [Nick Pentreath] Merge remote-tracking branch 'upstream/master' into pyspark-inputformats 795a763 [Nick Pentreath] Change name to WriteInputFormatTestDataGenerator. Cleanup some var names. Use SPARK_HOME in path for writing test sequencefile data. 174f520 [Nick Pentreath] Add back graphx settings 703ee65 [Nick Pentreath] Add back msgpack 619c0fa [Nick Pentreath] Merge remote-tracking branch 'upstream/master' into pyspark-inputformats 1c8efbc [Nick Pentreath] Merge remote-tracking branch 'upstream/master' into pyspark-inputformats eb40036 [Nick Pentreath] Remove unused comment lines 4d7ef2e [Nick Pentreath] Fix indentation f1d73e3 [Nick Pentreath] mergeConfs returns a copy rather than mutating one of the input arguments 0f5cd84 [Nick Pentreath] Remove unused pair UTF8 class. Add comments to msgpack deserializer 4294cbb [Nick Pentreath] Add old Hadoop api methods. Clean up and expand comments. Clean up argument names 818a1e6 [Nick Pentreath] Add seqencefile and Hadoop InputFormat support to PythonRDD 4e7c9e3 [Nick Pentreath] Merge remote-tracking branch 'upstream/master' into pyspark-inputformats c304cc8 [Nick Pentreath] Adding supporting sequncefiles for tests. Cleaning up 4b0a43f [Nick Pentreath] Refactoring utils into own objects. Cleaning up old commented-out code d86325f [Nick Pentreath] Initial WIP of PySpark support for SequenceFile and arbitrary Hadoop InputFormat
733 lines
31 KiB
Python
733 lines
31 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 shutil
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import sys
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from threading import Lock
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from tempfile import NamedTemporaryFile
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from collections import namedtuple
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from pyspark import accumulators
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from pyspark.accumulators import Accumulator
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from pyspark.broadcast import Broadcast
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from pyspark.conf import SparkConf
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from pyspark.files import SparkFiles
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from pyspark.java_gateway import launch_gateway
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from pyspark.serializers import PickleSerializer, BatchedSerializer, UTF8Deserializer, \
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PairDeserializer
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from pyspark.storagelevel import StorageLevel
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from pyspark import rdd
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from pyspark.rdd import RDD
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from py4j.java_collections import ListConverter
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class SparkContext(object):
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"""
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Main entry point for Spark functionality. A SparkContext represents the
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connection to a Spark cluster, and can be used to create L{RDD}s and
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broadcast variables on that cluster.
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"""
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_gateway = None
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_jvm = None
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_writeToFile = None
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_next_accum_id = 0
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_active_spark_context = None
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_lock = Lock()
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_python_includes = None # zip and egg files that need to be added to PYTHONPATH
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def __init__(self, master=None, appName=None, sparkHome=None, pyFiles=None,
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environment=None, batchSize=1024, serializer=PickleSerializer(), conf=None,
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gateway=None):
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"""
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Create a new SparkContext. At least the master and app name should be set,
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either through the named parameters here or through C{conf}.
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@param master: Cluster URL to connect to
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(e.g. mesos://host:port, spark://host:port, local[4]).
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@param appName: A name for your job, to display on the cluster web UI.
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@param sparkHome: Location where Spark is installed on cluster nodes.
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@param pyFiles: Collection of .zip or .py files to send to the cluster
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and add to PYTHONPATH. These can be paths on the local file
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system or HDFS, HTTP, HTTPS, or FTP URLs.
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@param environment: A dictionary of environment variables to set on
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worker nodes.
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@param batchSize: The number of Python objects represented as a single
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Java object. Set 1 to disable batching or -1 to use an
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unlimited batch size.
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@param serializer: The serializer for RDDs.
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@param conf: A L{SparkConf} object setting Spark properties.
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@param gateway: Use an existing gateway and JVM, otherwise a new JVM
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will be instatiated.
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>>> from pyspark.context import SparkContext
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>>> sc = SparkContext('local', 'test')
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>>> sc2 = SparkContext('local', 'test2') # doctest: +IGNORE_EXCEPTION_DETAIL
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Traceback (most recent call last):
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...
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ValueError:...
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"""
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if rdd._extract_concise_traceback() is not None:
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self._callsite = rdd._extract_concise_traceback()
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else:
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tempNamedTuple = namedtuple("Callsite", "function file linenum")
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self._callsite = tempNamedTuple(function=None, file=None, linenum=None)
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SparkContext._ensure_initialized(self, gateway=gateway)
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self.environment = environment or {}
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self._conf = conf or SparkConf(_jvm=self._jvm)
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self._batchSize = batchSize # -1 represents an unlimited batch size
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self._unbatched_serializer = serializer
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if batchSize == 1:
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self.serializer = self._unbatched_serializer
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else:
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self.serializer = BatchedSerializer(self._unbatched_serializer,
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batchSize)
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# Set any parameters passed directly to us on the conf
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if master:
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self._conf.setMaster(master)
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if appName:
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self._conf.setAppName(appName)
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if sparkHome:
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self._conf.setSparkHome(sparkHome)
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if environment:
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for key, value in environment.iteritems():
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self._conf.setExecutorEnv(key, value)
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# Check that we have at least the required parameters
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if not self._conf.contains("spark.master"):
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raise Exception("A master URL must be set in your configuration")
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if not self._conf.contains("spark.app.name"):
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raise Exception("An application name must be set in your configuration")
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# Read back our properties from the conf in case we loaded some of them from
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# the classpath or an external config file
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self.master = self._conf.get("spark.master")
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self.appName = self._conf.get("spark.app.name")
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self.sparkHome = self._conf.get("spark.home", None)
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for (k, v) in self._conf.getAll():
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if k.startswith("spark.executorEnv."):
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varName = k[len("spark.executorEnv."):]
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self.environment[varName] = v
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# Create the Java SparkContext through Py4J
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self._jsc = self._initialize_context(self._conf._jconf)
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# Create a single Accumulator in Java that we'll send all our updates through;
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# they will be passed back to us through a TCP server
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self._accumulatorServer = accumulators._start_update_server()
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(host, port) = self._accumulatorServer.server_address
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self._javaAccumulator = self._jsc.accumulator(
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self._jvm.java.util.ArrayList(),
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self._jvm.PythonAccumulatorParam(host, port))
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self.pythonExec = os.environ.get("PYSPARK_PYTHON", 'python')
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# Broadcast's __reduce__ method stores Broadcast instances here.
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# This allows other code to determine which Broadcast instances have
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# been pickled, so it can determine which Java broadcast objects to
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# send.
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self._pickled_broadcast_vars = set()
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SparkFiles._sc = self
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root_dir = SparkFiles.getRootDirectory()
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sys.path.append(root_dir)
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# Deploy any code dependencies specified in the constructor
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self._python_includes = list()
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for path in (pyFiles or []):
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self.addPyFile(path)
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# Deploy code dependencies set by spark-submit; these will already have been added
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# with SparkContext.addFile, so we just need to add them to the PYTHONPATH
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for path in self._conf.get("spark.submit.pyFiles", "").split(","):
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if path != "":
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(dirname, filename) = os.path.split(path)
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self._python_includes.append(filename)
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sys.path.append(path)
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if not dirname in sys.path:
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sys.path.append(dirname)
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# Create a temporary directory inside spark.local.dir:
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local_dir = self._jvm.org.apache.spark.util.Utils.getLocalDir(self._jsc.sc().conf())
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self._temp_dir = \
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self._jvm.org.apache.spark.util.Utils.createTempDir(local_dir).getAbsolutePath()
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def _initialize_context(self, jconf):
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"""
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Initialize SparkContext in function to allow subclass specific initialization
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"""
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return self._jvm.JavaSparkContext(jconf)
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@classmethod
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def _ensure_initialized(cls, instance=None, gateway=None):
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"""
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Checks whether a SparkContext is initialized or not.
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Throws error if a SparkContext is already running.
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"""
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with SparkContext._lock:
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if not SparkContext._gateway:
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SparkContext._gateway = gateway or launch_gateway()
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SparkContext._jvm = SparkContext._gateway.jvm
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SparkContext._writeToFile = SparkContext._jvm.PythonRDD.writeToFile
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if instance:
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if SparkContext._active_spark_context and SparkContext._active_spark_context != instance:
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currentMaster = SparkContext._active_spark_context.master
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currentAppName = SparkContext._active_spark_context.appName
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callsite = SparkContext._active_spark_context._callsite
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# Raise error if there is already a running Spark context
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raise ValueError("Cannot run multiple SparkContexts at once; existing SparkContext(app=%s, master=%s)" \
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" created by %s at %s:%s " \
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% (currentAppName, currentMaster, callsite.function, callsite.file, callsite.linenum))
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else:
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SparkContext._active_spark_context = instance
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@classmethod
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def setSystemProperty(cls, key, value):
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"""
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Set a Java system property, such as spark.executor.memory. This must
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must be invoked before instantiating SparkContext.
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"""
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SparkContext._ensure_initialized()
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SparkContext._jvm.java.lang.System.setProperty(key, value)
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@property
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def defaultParallelism(self):
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"""
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Default level of parallelism to use when not given by user (e.g. for
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reduce tasks)
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"""
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return self._jsc.sc().defaultParallelism()
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@property
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def defaultMinPartitions(self):
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"""
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Default min number of partitions for Hadoop RDDs when not given by user
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"""
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return self._jsc.sc().defaultMinPartitions()
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def __del__(self):
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self.stop()
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def stop(self):
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"""
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Shut down the SparkContext.
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"""
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if self._jsc:
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self._jsc.stop()
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self._jsc = None
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if self._accumulatorServer:
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self._accumulatorServer.shutdown()
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self._accumulatorServer = None
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with SparkContext._lock:
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SparkContext._active_spark_context = None
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def parallelize(self, c, numSlices=None):
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"""
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Distribute a local Python collection to form an RDD.
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>>> sc.parallelize(range(5), 5).glom().collect()
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[[0], [1], [2], [3], [4]]
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"""
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numSlices = numSlices or self.defaultParallelism
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# Calling the Java parallelize() method with an ArrayList is too slow,
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# because it sends O(n) Py4J commands. As an alternative, serialized
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# objects are written to a file and loaded through textFile().
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tempFile = NamedTemporaryFile(delete=False, dir=self._temp_dir)
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# Make sure we distribute data evenly if it's smaller than self.batchSize
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if "__len__" not in dir(c):
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c = list(c) # Make it a list so we can compute its length
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batchSize = min(len(c) // numSlices, self._batchSize)
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if batchSize > 1:
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serializer = BatchedSerializer(self._unbatched_serializer,
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batchSize)
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else:
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serializer = self._unbatched_serializer
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serializer.dump_stream(c, tempFile)
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tempFile.close()
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readRDDFromFile = self._jvm.PythonRDD.readRDDFromFile
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jrdd = readRDDFromFile(self._jsc, tempFile.name, numSlices)
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return RDD(jrdd, self, serializer)
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def pickleFile(self, name, minPartitions=None):
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"""
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Load an RDD previously saved using L{RDD.saveAsPickleFile} method.
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>>> tmpFile = NamedTemporaryFile(delete=True)
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>>> tmpFile.close()
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>>> sc.parallelize(range(10)).saveAsPickleFile(tmpFile.name, 5)
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>>> sorted(sc.pickleFile(tmpFile.name, 3).collect())
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[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
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"""
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minPartitions = minPartitions or self.defaultMinPartitions
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return RDD(self._jsc.objectFile(name, minPartitions), self,
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BatchedSerializer(PickleSerializer()))
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def textFile(self, name, minPartitions=None):
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"""
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Read a text file from HDFS, a local file system (available on all
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nodes), or any Hadoop-supported file system URI, and return it as an
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RDD of Strings.
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>>> path = os.path.join(tempdir, "sample-text.txt")
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>>> with open(path, "w") as testFile:
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... testFile.write("Hello world!")
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>>> textFile = sc.textFile(path)
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>>> textFile.collect()
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[u'Hello world!']
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"""
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minPartitions = minPartitions or min(self.defaultParallelism, 2)
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return RDD(self._jsc.textFile(name, minPartitions), self,
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UTF8Deserializer())
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def wholeTextFiles(self, path, minPartitions=None):
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"""
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Read a directory of text files from HDFS, a local file system
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(available on all nodes), or any Hadoop-supported file system
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URI. Each file is read as a single record and returned in a
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key-value pair, where the key is the path of each file, the
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value is the content of each file.
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For example, if you have the following files::
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hdfs://a-hdfs-path/part-00000
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hdfs://a-hdfs-path/part-00001
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...
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hdfs://a-hdfs-path/part-nnnnn
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Do C{rdd = sparkContext.wholeTextFiles("hdfs://a-hdfs-path")},
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then C{rdd} contains::
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(a-hdfs-path/part-00000, its content)
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(a-hdfs-path/part-00001, its content)
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...
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(a-hdfs-path/part-nnnnn, its content)
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NOTE: Small files are preferred, as each file will be loaded
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fully in memory.
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>>> dirPath = os.path.join(tempdir, "files")
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>>> os.mkdir(dirPath)
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>>> with open(os.path.join(dirPath, "1.txt"), "w") as file1:
|
|
... file1.write("1")
|
|
>>> with open(os.path.join(dirPath, "2.txt"), "w") as file2:
|
|
... file2.write("2")
|
|
>>> textFiles = sc.wholeTextFiles(dirPath)
|
|
>>> sorted(textFiles.collect())
|
|
[(u'.../1.txt', u'1'), (u'.../2.txt', u'2')]
|
|
"""
|
|
minPartitions = minPartitions or self.defaultMinPartitions
|
|
return RDD(self._jsc.wholeTextFiles(path, minPartitions), self,
|
|
PairDeserializer(UTF8Deserializer(), UTF8Deserializer()))
|
|
|
|
def _dictToJavaMap(self, d):
|
|
jm = self._jvm.java.util.HashMap()
|
|
if not d:
|
|
d = {}
|
|
for k, v in d.iteritems():
|
|
jm[k] = v
|
|
return jm
|
|
|
|
def sequenceFile(self, path, keyClass=None, valueClass=None, keyConverter=None,
|
|
valueConverter=None, minSplits=None):
|
|
"""
|
|
Read a Hadoop SequenceFile with arbitrary key and value Writable class from HDFS,
|
|
a local file system (available on all nodes), or any Hadoop-supported file system URI.
|
|
The mechanism is as follows:
|
|
1. A Java RDD is created from the SequenceFile or other InputFormat, and the key
|
|
and value Writable classes
|
|
2. Serialization is attempted via Pyrolite pickling
|
|
3. If this fails, the fallback is to call 'toString' on each key and value
|
|
4. C{PickleSerializer} is used to deserialize pickled objects on the Python side
|
|
|
|
@param path: path to sequncefile
|
|
@param keyClass: fully qualified classname of key Writable class
|
|
(e.g. "org.apache.hadoop.io.Text")
|
|
@param valueClass: fully qualified classname of value Writable class
|
|
(e.g. "org.apache.hadoop.io.LongWritable")
|
|
@param keyConverter:
|
|
@param valueConverter:
|
|
@param minSplits: minimum splits in dataset
|
|
(default min(2, sc.defaultParallelism))
|
|
"""
|
|
minSplits = minSplits or min(self.defaultParallelism, 2)
|
|
jrdd = self._jvm.PythonRDD.sequenceFile(self._jsc, path, keyClass, valueClass,
|
|
keyConverter, valueConverter, minSplits)
|
|
return RDD(jrdd, self, PickleSerializer())
|
|
|
|
def newAPIHadoopFile(self, path, inputFormatClass, keyClass, valueClass, keyConverter=None,
|
|
valueConverter=None, conf=None):
|
|
"""
|
|
Read a 'new API' Hadoop InputFormat with arbitrary key and value class from HDFS,
|
|
a local file system (available on all nodes), or any Hadoop-supported file system URI.
|
|
The mechanism is the same as for sc.sequenceFile.
|
|
|
|
A Hadoop configuration can be passed in as a Python dict. This will be converted into a
|
|
Configuration in Java
|
|
|
|
@param path: path to Hadoop file
|
|
@param inputFormatClass: fully qualified classname of Hadoop InputFormat
|
|
(e.g. "org.apache.hadoop.mapreduce.lib.input.TextInputFormat")
|
|
@param keyClass: fully qualified classname of key Writable class
|
|
(e.g. "org.apache.hadoop.io.Text")
|
|
@param valueClass: fully qualified classname of value Writable class
|
|
(e.g. "org.apache.hadoop.io.LongWritable")
|
|
@param keyConverter: (None by default)
|
|
@param valueConverter: (None by default)
|
|
@param conf: Hadoop configuration, passed in as a dict
|
|
(None by default)
|
|
"""
|
|
jconf = self._dictToJavaMap(conf)
|
|
jrdd = self._jvm.PythonRDD.newAPIHadoopFile(self._jsc, path, inputFormatClass, keyClass,
|
|
valueClass, keyConverter, valueConverter, jconf)
|
|
return RDD(jrdd, self, PickleSerializer())
|
|
|
|
def newAPIHadoopRDD(self, inputFormatClass, keyClass, valueClass, keyConverter=None,
|
|
valueConverter=None, conf=None):
|
|
"""
|
|
Read a 'new API' Hadoop InputFormat with arbitrary key and value class, from an arbitrary
|
|
Hadoop configuration, which is passed in as a Python dict.
|
|
This will be converted into a Configuration in Java.
|
|
The mechanism is the same as for sc.sequenceFile.
|
|
|
|
@param inputFormatClass: fully qualified classname of Hadoop InputFormat
|
|
(e.g. "org.apache.hadoop.mapreduce.lib.input.TextInputFormat")
|
|
@param keyClass: fully qualified classname of key Writable class
|
|
(e.g. "org.apache.hadoop.io.Text")
|
|
@param valueClass: fully qualified classname of value Writable class
|
|
(e.g. "org.apache.hadoop.io.LongWritable")
|
|
@param keyConverter: (None by default)
|
|
@param valueConverter: (None by default)
|
|
@param conf: Hadoop configuration, passed in as a dict
|
|
(None by default)
|
|
"""
|
|
jconf = self._dictToJavaMap(conf)
|
|
jrdd = self._jvm.PythonRDD.newAPIHadoopRDD(self._jsc, inputFormatClass, keyClass,
|
|
valueClass, keyConverter, valueConverter, jconf)
|
|
return RDD(jrdd, self, PickleSerializer())
|
|
|
|
def hadoopFile(self, path, inputFormatClass, keyClass, valueClass, keyConverter=None,
|
|
valueConverter=None, conf=None):
|
|
"""
|
|
Read an 'old' Hadoop InputFormat with arbitrary key and value class from HDFS,
|
|
a local file system (available on all nodes), or any Hadoop-supported file system URI.
|
|
The mechanism is the same as for sc.sequenceFile.
|
|
|
|
A Hadoop configuration can be passed in as a Python dict. This will be converted into a
|
|
Configuration in Java.
|
|
|
|
@param path: path to Hadoop file
|
|
@param inputFormatClass: fully qualified classname of Hadoop InputFormat
|
|
(e.g. "org.apache.hadoop.mapred.TextInputFormat")
|
|
@param keyClass: fully qualified classname of key Writable class
|
|
(e.g. "org.apache.hadoop.io.Text")
|
|
@param valueClass: fully qualified classname of value Writable class
|
|
(e.g. "org.apache.hadoop.io.LongWritable")
|
|
@param keyConverter: (None by default)
|
|
@param valueConverter: (None by default)
|
|
@param conf: Hadoop configuration, passed in as a dict
|
|
(None by default)
|
|
"""
|
|
jconf = self._dictToJavaMap(conf)
|
|
jrdd = self._jvm.PythonRDD.hadoopFile(self._jsc, path, inputFormatClass, keyClass,
|
|
valueClass, keyConverter, valueConverter, jconf)
|
|
return RDD(jrdd, self, PickleSerializer())
|
|
|
|
def hadoopRDD(self, inputFormatClass, keyClass, valueClass, keyConverter=None,
|
|
valueConverter=None, conf=None):
|
|
"""
|
|
Read an 'old' Hadoop InputFormat with arbitrary key and value class, from an arbitrary
|
|
Hadoop configuration, which is passed in as a Python dict.
|
|
This will be converted into a Configuration in Java.
|
|
The mechanism is the same as for sc.sequenceFile.
|
|
|
|
@param inputFormatClass: fully qualified classname of Hadoop InputFormat
|
|
(e.g. "org.apache.hadoop.mapred.TextInputFormat")
|
|
@param keyClass: fully qualified classname of key Writable class
|
|
(e.g. "org.apache.hadoop.io.Text")
|
|
@param valueClass: fully qualified classname of value Writable class
|
|
(e.g. "org.apache.hadoop.io.LongWritable")
|
|
@param keyConverter: (None by default)
|
|
@param valueConverter: (None by default)
|
|
@param conf: Hadoop configuration, passed in as a dict
|
|
(None by default)
|
|
"""
|
|
jconf = self._dictToJavaMap(conf)
|
|
jrdd = self._jvm.PythonRDD.hadoopRDD(self._jsc, inputFormatClass, keyClass, valueClass,
|
|
keyConverter, valueConverter, jconf)
|
|
return RDD(jrdd, self, PickleSerializer())
|
|
|
|
def _checkpointFile(self, name, input_deserializer):
|
|
jrdd = self._jsc.checkpointFile(name)
|
|
return RDD(jrdd, self, input_deserializer)
|
|
|
|
def union(self, rdds):
|
|
"""
|
|
Build the union of a list of RDDs.
|
|
|
|
This supports unions() of RDDs with different serialized formats,
|
|
although this forces them to be reserialized using the default
|
|
serializer:
|
|
|
|
>>> path = os.path.join(tempdir, "union-text.txt")
|
|
>>> with open(path, "w") as testFile:
|
|
... testFile.write("Hello")
|
|
>>> textFile = sc.textFile(path)
|
|
>>> textFile.collect()
|
|
[u'Hello']
|
|
>>> parallelized = sc.parallelize(["World!"])
|
|
>>> sorted(sc.union([textFile, parallelized]).collect())
|
|
[u'Hello', 'World!']
|
|
"""
|
|
first_jrdd_deserializer = rdds[0]._jrdd_deserializer
|
|
if any(x._jrdd_deserializer != first_jrdd_deserializer for x in rdds):
|
|
rdds = [x._reserialize() for x in rdds]
|
|
first = rdds[0]._jrdd
|
|
rest = [x._jrdd for x in rdds[1:]]
|
|
rest = ListConverter().convert(rest, self._gateway._gateway_client)
|
|
return RDD(self._jsc.union(first, rest), self,
|
|
rdds[0]._jrdd_deserializer)
|
|
|
|
def broadcast(self, value):
|
|
"""
|
|
Broadcast a read-only variable to the cluster, returning a
|
|
L{Broadcast<pyspark.broadcast.Broadcast>}
|
|
object for reading it in distributed functions. The variable will be
|
|
sent to each cluster only once.
|
|
"""
|
|
pickleSer = PickleSerializer()
|
|
pickled = pickleSer.dumps(value)
|
|
jbroadcast = self._jsc.broadcast(bytearray(pickled))
|
|
return Broadcast(jbroadcast.id(), value, jbroadcast,
|
|
self._pickled_broadcast_vars)
|
|
|
|
def accumulator(self, value, accum_param=None):
|
|
"""
|
|
Create an L{Accumulator} with the given initial value, using a given
|
|
L{AccumulatorParam} helper object to define how to add values of the
|
|
data type if provided. Default AccumulatorParams are used for integers
|
|
and floating-point numbers if you do not provide one. For other types,
|
|
a custom AccumulatorParam can be used.
|
|
"""
|
|
if accum_param is None:
|
|
if isinstance(value, int):
|
|
accum_param = accumulators.INT_ACCUMULATOR_PARAM
|
|
elif isinstance(value, float):
|
|
accum_param = accumulators.FLOAT_ACCUMULATOR_PARAM
|
|
elif isinstance(value, complex):
|
|
accum_param = accumulators.COMPLEX_ACCUMULATOR_PARAM
|
|
else:
|
|
raise Exception("No default accumulator param for type %s" % type(value))
|
|
SparkContext._next_accum_id += 1
|
|
return Accumulator(SparkContext._next_accum_id - 1, value, accum_param)
|
|
|
|
def addFile(self, path):
|
|
"""
|
|
Add a file to be downloaded with this Spark job on every node.
|
|
The C{path} passed can be either a local file, a file in HDFS
|
|
(or other Hadoop-supported filesystems), or an HTTP, HTTPS or
|
|
FTP URI.
|
|
|
|
To access the file in Spark jobs, use
|
|
L{SparkFiles.get(path)<pyspark.files.SparkFiles.get>} to find its
|
|
download location.
|
|
|
|
>>> from pyspark import SparkFiles
|
|
>>> path = os.path.join(tempdir, "test.txt")
|
|
>>> with open(path, "w") as testFile:
|
|
... testFile.write("100")
|
|
>>> sc.addFile(path)
|
|
>>> def func(iterator):
|
|
... with open(SparkFiles.get("test.txt")) as testFile:
|
|
... fileVal = int(testFile.readline())
|
|
... return [x * 100 for x in iterator]
|
|
>>> sc.parallelize([1, 2, 3, 4]).mapPartitions(func).collect()
|
|
[100, 200, 300, 400]
|
|
"""
|
|
self._jsc.sc().addFile(path)
|
|
|
|
def clearFiles(self):
|
|
"""
|
|
Clear the job's list of files added by L{addFile} or L{addPyFile} so
|
|
that they do not get downloaded to any new nodes.
|
|
"""
|
|
# TODO: remove added .py or .zip files from the PYTHONPATH?
|
|
self._jsc.sc().clearFiles()
|
|
|
|
def addPyFile(self, path):
|
|
"""
|
|
Add a .py or .zip dependency for all tasks to be executed on this
|
|
SparkContext in the future. The C{path} passed can be either a local
|
|
file, a file in HDFS (or other Hadoop-supported filesystems), or an
|
|
HTTP, HTTPS or FTP URI.
|
|
"""
|
|
self.addFile(path)
|
|
(dirname, filename) = os.path.split(path) # dirname may be directory or HDFS/S3 prefix
|
|
|
|
if filename.endswith('.zip') or filename.endswith('.ZIP') or filename.endswith('.egg'):
|
|
self._python_includes.append(filename)
|
|
sys.path.append(os.path.join(SparkFiles.getRootDirectory(), filename)) # for tests in local mode
|
|
|
|
def setCheckpointDir(self, dirName):
|
|
"""
|
|
Set the directory under which RDDs are going to be checkpointed. The
|
|
directory must be a HDFS path if running on a cluster.
|
|
"""
|
|
self._jsc.sc().setCheckpointDir(dirName)
|
|
|
|
def _getJavaStorageLevel(self, storageLevel):
|
|
"""
|
|
Returns a Java StorageLevel based on a pyspark.StorageLevel.
|
|
"""
|
|
if not isinstance(storageLevel, StorageLevel):
|
|
raise Exception("storageLevel must be of type pyspark.StorageLevel")
|
|
|
|
newStorageLevel = self._jvm.org.apache.spark.storage.StorageLevel
|
|
return newStorageLevel(storageLevel.useDisk,
|
|
storageLevel.useMemory,
|
|
storageLevel.useOffHeap,
|
|
storageLevel.deserialized,
|
|
storageLevel.replication)
|
|
|
|
def setJobGroup(self, groupId, description, interruptOnCancel=False):
|
|
"""
|
|
Assigns a group ID to all the jobs started by this thread until the group ID is set to a
|
|
different value or cleared.
|
|
|
|
Often, a unit of execution in an application consists of multiple Spark actions or jobs.
|
|
Application programmers can use this method to group all those jobs together and give a
|
|
group description. Once set, the Spark web UI will associate such jobs with this group.
|
|
|
|
The application can use L{SparkContext.cancelJobGroup} to cancel all
|
|
running jobs in this group.
|
|
|
|
>>> import thread, threading
|
|
>>> from time import sleep
|
|
>>> result = "Not Set"
|
|
>>> lock = threading.Lock()
|
|
>>> def map_func(x):
|
|
... sleep(100)
|
|
... raise Exception("Task should have been cancelled")
|
|
>>> def start_job(x):
|
|
... global result
|
|
... try:
|
|
... sc.setJobGroup("job_to_cancel", "some description")
|
|
... result = sc.parallelize(range(x)).map(map_func).collect()
|
|
... except Exception as e:
|
|
... result = "Cancelled"
|
|
... lock.release()
|
|
>>> def stop_job():
|
|
... sleep(5)
|
|
... sc.cancelJobGroup("job_to_cancel")
|
|
>>> supress = lock.acquire()
|
|
>>> supress = thread.start_new_thread(start_job, (10,))
|
|
>>> supress = thread.start_new_thread(stop_job, tuple())
|
|
>>> supress = lock.acquire()
|
|
>>> print result
|
|
Cancelled
|
|
|
|
If interruptOnCancel is set to true for the job group, then job cancellation will result
|
|
in Thread.interrupt() being called on the job's executor threads. This is useful to help ensure
|
|
that the tasks are actually stopped in a timely manner, but is off by default due to HDFS-1208,
|
|
where HDFS may respond to Thread.interrupt() by marking nodes as dead.
|
|
"""
|
|
self._jsc.setJobGroup(groupId, description, interruptOnCancel)
|
|
|
|
def setLocalProperty(self, key, value):
|
|
"""
|
|
Set a local property that affects jobs submitted from this thread, such as the
|
|
Spark fair scheduler pool.
|
|
"""
|
|
self._jsc.setLocalProperty(key, value)
|
|
|
|
def getLocalProperty(self, key):
|
|
"""
|
|
Get a local property set in this thread, or null if it is missing. See
|
|
L{setLocalProperty}
|
|
"""
|
|
return self._jsc.getLocalProperty(key)
|
|
|
|
def sparkUser(self):
|
|
"""
|
|
Get SPARK_USER for user who is running SparkContext.
|
|
"""
|
|
return self._jsc.sc().sparkUser()
|
|
|
|
def cancelJobGroup(self, groupId):
|
|
"""
|
|
Cancel active jobs for the specified group. See L{SparkContext.setJobGroup}
|
|
for more information.
|
|
"""
|
|
self._jsc.sc().cancelJobGroup(groupId)
|
|
|
|
def cancelAllJobs(self):
|
|
"""
|
|
Cancel all jobs that have been scheduled or are running.
|
|
"""
|
|
self._jsc.sc().cancelAllJobs()
|
|
|
|
def runJob(self, rdd, partitionFunc, partitions = None, allowLocal = False):
|
|
"""
|
|
Executes the given partitionFunc on the specified set of partitions,
|
|
returning the result as an array of elements.
|
|
|
|
If 'partitions' is not specified, this will run over all partitions.
|
|
|
|
>>> myRDD = sc.parallelize(range(6), 3)
|
|
>>> sc.runJob(myRDD, lambda part: [x * x for x in part])
|
|
[0, 1, 4, 9, 16, 25]
|
|
|
|
>>> myRDD = sc.parallelize(range(6), 3)
|
|
>>> sc.runJob(myRDD, lambda part: [x * x for x in part], [0, 2], True)
|
|
[0, 1, 16, 25]
|
|
"""
|
|
if partitions == None:
|
|
partitions = range(rdd._jrdd.splits().size())
|
|
javaPartitions = ListConverter().convert(partitions, self._gateway._gateway_client)
|
|
|
|
# Implementation note: This is implemented as a mapPartitions followed
|
|
# by runJob() in order to avoid having to pass a Python lambda into
|
|
# SparkContext#runJob.
|
|
mappedRDD = rdd.mapPartitions(partitionFunc)
|
|
it = self._jvm.PythonRDD.runJob(self._jsc.sc(), mappedRDD._jrdd, javaPartitions, allowLocal)
|
|
return list(mappedRDD._collect_iterator_through_file(it))
|
|
|
|
def _test():
|
|
import atexit
|
|
import doctest
|
|
import tempfile
|
|
globs = globals().copy()
|
|
globs['sc'] = SparkContext('local[4]', 'PythonTest', batchSize=2)
|
|
globs['tempdir'] = tempfile.mkdtemp()
|
|
atexit.register(lambda: shutil.rmtree(globs['tempdir']))
|
|
(failure_count, test_count) = doctest.testmod(globs=globs, optionflags=doctest.ELLIPSIS)
|
|
globs['sc'].stop()
|
|
if failure_count:
|
|
exit(-1)
|
|
|
|
|
|
if __name__ == "__main__":
|
|
_test()
|