spark BroadcastManager 源码
spark BroadcastManager 代码
文件路径：/core/src/main/scala/org/apache/spark/broadcast/BroadcastManager.scala
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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.
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package org.apache.spark.broadcast
import java.util.Collections
import java.util.concurrent.atomic.AtomicLong
import scala.reflect.ClassTag
import org.apache.commons.collections4.map.AbstractReferenceMap.ReferenceStrength
import org.apache.commons.collections4.map.ReferenceMap
import org.apache.spark.SparkConf
import org.apache.spark.api.python.PythonBroadcast
import org.apache.spark.internal.Logging
private[spark] class BroadcastManager(
val isDriver: Boolean, conf: SparkConf) extends Logging {
private var initialized = false
private var broadcastFactory: BroadcastFactory = null
initialize()
// Called by SparkContext or Executor before using Broadcast
private def initialize(): Unit = {
synchronized {
if (!initialized) {
broadcastFactory = new TorrentBroadcastFactory
broadcastFactory.initialize(isDriver, conf)
initialized = true
}
}
}
def stop(): Unit = {
broadcastFactory.stop()
}
private val nextBroadcastId = new AtomicLong(0)
private[broadcast] val cachedValues =
Collections.synchronizedMap(
new ReferenceMap(ReferenceStrength.HARD, ReferenceStrength.WEAK)
.asInstanceOf[java.util.Map[Any, Any]]
)
def newBroadcast[T: ClassTag](
value_ : T,
isLocal: Boolean,
serializedOnly: Boolean = false): Broadcast[T] = {
val bid = nextBroadcastId.getAndIncrement()
value_ match {
case pb: PythonBroadcast =>
// SPARK-28486: attach this new broadcast variable's id to the PythonBroadcast,
// so that underlying data file of PythonBroadcast could be mapped to the
// BroadcastBlockId according to this id. Please see the specific usage of the
// id in PythonBroadcast.readObject().
pb.setBroadcastId(bid)
case _ => // do nothing
}
broadcastFactory.newBroadcast[T](value_, isLocal, bid, serializedOnly)
}
def unbroadcast(id: Long, removeFromDriver: Boolean, blocking: Boolean): Unit = {
broadcastFactory.unbroadcast(id, removeFromDriver, blocking)
}
}
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