org.apache.spark.storage.TopologyMapper.scala Maven / Gradle / Ivy
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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,
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* See the License for the specific language governing permissions and
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package org.apache.spark.storage
import org.apache.spark.SparkConf
import org.apache.spark.annotation.DeveloperApi
import org.apache.spark.internal.{config, Logging}
import org.apache.spark.util.Utils
/**
* ::DeveloperApi::
* TopologyMapper provides topology information for a given host
* @param conf SparkConf to get required properties, if needed
*/
@DeveloperApi
abstract class TopologyMapper(conf: SparkConf) {
/**
* Gets the topology information given the host name
*
* @param hostname Hostname
* @return topology information for the given hostname. One can use a 'topology delimiter'
* to make this topology information nested.
* For example : ‘/myrack/myhost’, where ‘/’ is the topology delimiter,
* ‘myrack’ is the topology identifier, and ‘myhost’ is the individual host.
* This function only returns the topology information without the hostname.
* This information can be used when choosing executors for block replication
* to discern executors from a different rack than a candidate executor, for example.
*
* An implementation can choose to use empty strings or None in case topology info
* is not available. This would imply that all such executors belong to the same rack.
*/
def getTopologyForHost(hostname: String): Option[String]
}
/**
* A TopologyMapper that assumes all nodes are in the same rack
*/
@DeveloperApi
class DefaultTopologyMapper(conf: SparkConf) extends TopologyMapper(conf) with Logging {
override def getTopologyForHost(hostname: String): Option[String] = {
logDebug(s"Got a request for $hostname")
None
}
}
/**
* A simple file based topology mapper. This expects topology information provided as a
* `java.util.Properties` file. The name of the file is obtained from SparkConf property
* `spark.storage.replication.topologyFile`. To use this topology mapper, set the
* `spark.storage.replication.topologyMapper` property to
* [[org.apache.spark.storage.FileBasedTopologyMapper]]
* @param conf SparkConf object
*/
@DeveloperApi
class FileBasedTopologyMapper(conf: SparkConf) extends TopologyMapper(conf) with Logging {
val topologyFile = conf.get(config.STORAGE_REPLICATION_TOPOLOGY_FILE)
require(topologyFile.isDefined, "Please specify topology file via " +
"spark.storage.replication.topologyFile for FileBasedTopologyMapper.")
val topologyMap = Utils.getPropertiesFromFile(topologyFile.get)
override def getTopologyForHost(hostname: String): Option[String] = {
val topology = topologyMap.get(hostname)
if (topology.isDefined) {
logDebug(s"$hostname -> ${topology.get}")
} else {
logWarning(s"$hostname does not have any topology information")
}
topology
}
}