小贝子编程

Spark 2.1 在读取大型数据集时挂起



在我的应用程序中，我比较了两个不同的数据集(即来自 Hive 的源表和来自 RDBMS 的目标(的重复和不匹配，它适用于较小的数据集，但是当我尝试比较超过 1GB(仅源(的数据时，它会挂起并抛出TIMEOUT ERROR，即使在增加网络超时后，我也尝试.config("spark.network.timeout", "600s")抛出java.lang.OutOfMemoryError: GC overhead limit exceeded。

val spark = SparkSession.builder().master("local")
.appName("spark remote")
.config("javax.jdo.option.ConnectionURL", "jdbc:mysql://192.168.175.160:3306/metastore?useSSL=false")
.config("javax.jdo.option.ConnectionUserName", "hiveroot")
.config("javax.jdo.option.ConnectionPassword", "hivepassword")
.config("hive.exec.scratchdir", "/tmp/hive/${user.name}")
.config("hive.metastore.uris", "thrift://192.168.175.160:9083")    
.enableHiveSupport()
.getOrCreate()
import spark.implicits._
import spark.sql
val source = spark.sql("SELECT * from sample.source").rdd.map(_.mkString(","))
SparkSession.clearActiveSession()
SparkSession.clearDefaultSession()
val sparkdestination = SparkSession.builder().master("local").appName("Database")
.config("spark.network.timeout", "600s")
.getOrCreate()
val jdbcUsername = "root"
val jdbcPassword = "root"
val url = "jdbc:mysql://192.168.175.35:3306/sample?useSSL=false"
val connectionProperties = new java.util.Properties()
connectionProperties.put("user", jdbcUsername)
connectionProperties.put("password", jdbcPassword)
val queryDestination = "(select * from destination) as dest"
val destination = sparkdestination.read.jdbc(url, queryDestination, connectionProperties).rdd.map(_.mkString(","))

我也尝试了destination.persist(StorageLevel.MEMORY_AND_DISK_SER)(MEMORY_AND_DISK，DISK_ONLY(方法，但没有运气。

编辑：这是原始错误堆栈：

17/07/11 12:49:43 INFO DAGScheduler: Submitting 22 missing tasks from ShuffleMapStage 1 (MapPartitionsRDD[13] at map at stack.scala:76)
17/07/11 12:49:43 INFO TaskSchedulerImpl: Adding task set 1.0 with 22 tasks
17/07/11 12:49:43 INFO Executor: Running task 0.0 in stage 0.0 (TID 0)
17/07/11 12:51:38 INFO JDBCRDD: closed connection
17/07/11 12:51:38 ERROR Executor: Exception in task 0.0 in stage 0.0 (TID 0)
java.lang.OutOfMemoryError: GC overhead limit exceeded
at com.mysql.jdbc.MysqlIO.nextRowFast(MysqlIO.java:2210)
at com.mysql.jdbc.MysqlIO.nextRow(MysqlIO.java:1989)
at com.mysql.jdbc.MysqlIO.readSingleRowSet(MysqlIO.java:3410)
at com.mysql.jdbc.MysqlIO.getResultSet(MysqlIO.java:470)
at com.mysql.jdbc.MysqlIO.readResultsForQueryOrUpdate(MysqlIO.java:3112)
at com.mysql.jdbc.MysqlIO.readAllResults(MysqlIO.java:2341)
at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2736)
at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2490)
at com.mysql.jdbc.PreparedStatement.executeInternal(PreparedStatement.java:1858)
at com.mysql.jdbc.PreparedStatement.executeQuery(PreparedStatement.java:1966)
at org.apache.spark.sql.execution.datasources.jdbc.JDBCRDD.compute(JDBCRDD.scala:301)
at org.apache.spark.rdd.RDD.computeOrReadCheckpoint(RDD.scala:323)
at org.apache.spark.rdd.RDD.iterator(RDD.scala:287)
at org.apache.spark.rdd.MapPartitionsRDD.compute(MapPartitionsRDD.scala:38)
at org.apache.spark.rdd.RDD.computeOrReadCheckpoint(RDD.scala:323)
at org.apache.spark.rdd.RDD.iterator(RDD.scala:287)
at org.apache.spark.rdd.MapPartitionsRDD.compute(MapPartitionsRDD.scala:38)
at org.apache.spark.rdd.RDD.computeOrReadCheckpoint(RDD.scala:323)
at org.apache.spark.rdd.RDD.iterator(RDD.scala:287)
at org.apache.spark.rdd.MapPartitionsRDD.compute(MapPartitionsRDD.scala:38)
at org.apache.spark.rdd.RDD.computeOrReadCheckpoint(RDD.scala:323)
at org.apache.spark.rdd.RDD.iterator(RDD.scala:287)
at org.apache.spark.rdd.MapPartitionsRDD.compute(MapPartitionsRDD.scala:38)
at org.apache.spark.rdd.RDD.computeOrReadCheckpoint(RDD.scala:323)
at org.apache.spark.rdd.RDD.iterator(RDD.scala:287)
at org.apache.spark.rdd.MapPartitionsRDD.compute(MapPartitionsRDD.scala:38)
at org.apache.spark.rdd.RDD.computeOrReadCheckpoint(RDD.scala:323)
at org.apache.spark.rdd.RDD.iterator(RDD.scala:287)
at org.apache.spark.rdd.MapPartitionsRDD.compute(MapPartitionsRDD.scala:38)
at org.apache.spark.rdd.RDD.computeOrReadCheckpoint(RDD.scala:323)
at org.apache.spark.rdd.RDD.iterator(RDD.scala:287)
at org.apache.spark.scheduler.ShuffleMapTask.runTask(ShuffleMapTask.scala:96)
17/07/11 12:51:38 ERROR SparkUncaughtExceptionHandler: Uncaught exception in thread Thread[Executor task launch worker-0,5,main]
java.lang.OutOfMemoryError: GC overhead limit exceeded
at com.mysql.jdbc.MysqlIO.nextRowFast(MysqlIO.java:2210)
at com.mysql.jdbc.MysqlIO.nextRow(MysqlIO.java:1989)
17/07/11 12:49:43 INFO DAGScheduler: Submitting 22 missing tasks from ShuffleMapStage 1 (MapPartitionsRDD[13] at map at stack.scala:76)
17/07/11 12:49:43 INFO TaskSchedulerImpl: Adding task set 1.0 with 22 tasks
17/07/11 12:49:43 INFO Executor: Running task 0.0 in stage 0.0 (TID 0)
17/07/11 12:51:38 INFO JDBCRDD: closed connection
17/07/11 12:51:38 ERROR Executor: Exception in task 0.0 in stage 0.0 (TID 0)
java.lang.OutOfMemoryError: GC overhead limit exceeded
at com.mysql.jdbc.MysqlIO.nextRowFast(MysqlIO.java:2210)
at com.mysql.jdbc.MysqlIO.nextRow(MysqlIO.java:1989)
at com.mysql.jdbc.MysqlIO.readSingleRowSet(MysqlIO.java:3410)
at com.mysql.jdbc.MysqlIO.getResultSet(MysqlIO.java:470)
at com.mysql.jdbc.MysqlIO.readResultsForQueryOrUpdate(MysqlIO.java:3112)
at com.mysql.jdbc.MysqlIO.readAllResults(MysqlIO.java:2341)
at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2736)
at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2490)
at com.mysql.jdbc.PreparedStatement.executeInternal(PreparedStatement.java:1858)
at com.mysql.jdbc.PreparedStatement.executeQuery(PreparedStatement.java:1966)
at org.apache.spark.sql.execution.datasources.jdbc.JDBCRDD.compute(JDBCRDD.scala:301)
at org.apache.spark.rdd.RDD.computeOrReadCheckpoint(RDD.scala:323)
at org.apache.spark.rdd.RDD.iterator(RDD.scala:287)
at org.apache.spark.rdd.MapPartitionsRDD.compute(MapPartitionsRDD.scala:38)
at org.apache.spark.rdd.RDD.computeOrReadCheckpoint(RDD.scala:323)
at org.apache.spark.rdd.RDD.iterator(RDD.scala:287)
at org.apache.spark.rdd.MapPartitionsRDD.compute(MapPartitionsRDD.scala:38)
at org.apache.spark.rdd.RDD.computeOrReadCheckpoint(RDD.scala:323)
at org.apache.spark.rdd.RDD.iterator(RDD.scala:287)
at org.apache.spark.rdd.MapPartitionsRDD.compute(MapPartitionsRDD.scala:38)
at org.apache.spark.rdd.RDD.computeOrReadCheckpoint(RDD.scala:323)
at org.apache.spark.rdd.RDD.iterator(RDD.scala:287)
at org.apache.spark.rdd.MapPartitionsRDD.compute(MapPartitionsRDD.scala:38)
at org.apache.spark.rdd.RDD.computeOrReadCheckpoint(RDD.scala:323)
at org.apache.spark.rdd.RDD.iterator(RDD.scala:287)
at org.apache.spark.rdd.MapPartitionsRDD.compute(MapPartitionsRDD.scala:38)
at org.apache.spark.rdd.RDD.computeOrReadCheckpoint(RDD.scala:323)
at org.apache.spark.rdd.RDD.iterator(RDD.scala:287)
at org.apache.spark.rdd.MapPartitionsRDD.compute(MapPartitionsRDD.scala:38)
at org.apache.spark.rdd.RDD.computeOrReadCheckpoint(RDD.scala:323)
at org.apache.spark.rdd.RDD.iterator(RDD.scala:287)
at org.apache.spark.scheduler.ShuffleMapTask.runTask(ShuffleMapTask.scala:96)
17/07/11 12:51:38 ERROR SparkUncaughtExceptionHandler: Uncaught exception in thread Thread[Executor task launch worker-0,5,main]
java.lang.OutOfMemoryError: GC overhead limit exceeded
at com.mysql.jdbc.MysqlIO.nextRowFast(MysqlIO.java:2210)
at com.mysql.jdbc.MysqlIO.nextRow(MysqlIO.java:1989)

编辑2：

我尝试使用：

val options = Map(
"url" -> "jdbc:mysql://192.168.175.35:3306/sample?useSSL=false",
"dbtable" -> queryDestination,
"user" -> "root",
"password" -> "root")
val destination = sparkdestination.read.options(options).jdbc(options("url"), options("dbtable"), "0", 1, 5, 4, new java.util.Properties()).rdd.map(_.mkString(","))

我检查了少量数据它的工作，但对于大型数据集，它会抛出下面的错误

ERROR

17/07/11 14:12:46 INFO DAGScheduler: looking for newly runnable stages
17/07/11 14:12:46 INFO DAGScheduler: running: Set(ShuffleMapStage 1)
17/07/11 14:12:46 INFO DAGScheduler: waiting: Set(ResultStage 2)
17/07/11 14:12:46 INFO DAGScheduler: failed: Set()
17/07/11 14:12:50 INFO BlockManagerInfo: Removed broadcast_1_piece0 on 192.168.175.160:39913 in memory (size: 19.9 KB, free: 353.4 MB)
17/07/11 14:14:47 WARN ServerConnector: 
17/07/11 14:15:32 WARN QueuedThreadPool: 
java.lang.OutOfMemoryError: GC overhead limit exceeded
at java.lang.String.substring(String.java:1969)
17/07/11 14:15:32 ERROR Utils: uncaught error in thread Spark Context Cleaner, stopping SparkContext
java.lang.OutOfMemoryError: GC overhead limit exceeded
at org.apache.spark.ContextCleaner$$anonfun$org$apache$spark$ContextCleaner$$keepCleaning$1.apply$mcV$sp(ContextCleaner.scala:179)
17/07/11 14:15:32 WARN NettyRpcEndpointRef: Error sending message [message = Heartbeat(driver,      [Lscala.Tuple2;@1e855db,BlockManagerId  (driver, 192.168.175.160, 39913, None))] in 1 attempts
org.apache.spark.rpc.RpcTimeoutException: Futures timed out after [10 seconds]. This timeout is controlled by   spark.executor.heartbeatInterval
at org.apache.spark.rpc.RpcTimeout.org$apache$spark$rpc$RpcTimeout$$createRpcTimeoutException(RpcTimeout.scala:48)
at org.apache.spark.rpc.RpcTimeout$$anonfun$addMessageIfTimeout$1.applyOrElse(RpcTimeout.scala:63)
Caused by: java.util.concurrent.TimeoutException: Futures timed out after [10 seconds]
at scala.concurrent.impl.Promise$DefaultPromise.ready(Promise.scala:219)
17/07/11 14:15:32 ERROR Utils: throw uncaught fatal error in thread Spark Context Cleaner
java.lang.OutOfMemoryError: GC overhead limit exceeded
at org.apache.spark.ContextCleaner$$anonfun$org$apache$spark$ContextCleaner$$keepCleaning$1.apply$mcV$sp(ContextCleaner.scala:179)
at org.apache.spark.util.Utils$.tryOrStopSparkContext(Utils.scala:1245)
17/07/11 14:15:32 WARN QueuedThreadPool: Unexpected thread death: org.spark_project.jetty.util.thread.QueuedThreadPool$3@710104 in  SparkUI{STARTED,8<=8<=200,i=5,q=0}
17/07/11 14:15:32 INFO JDBCRDD: closed connection
17/07/11 14:15:32 ERROR Executor: Exception in task 0.0 in stage 1.0 (TID 22)
java.lang.OutOfMemoryError: GC overhead limit exceeded
17/07/11 14:15:32 INFO SparkUI: Stopped Spark web UI at http://192.168.175.160:4040
17/07/11 14:15:32 INFO DAGScheduler: Job 0 failed: collect at stack.scala:93, took 294.365864 s
Exception in thread "main" org.apache.spark.SparkException: Job 0 cancelled because SparkContext was shut down
at org.apache.spark.scheduler.DAGScheduler$$anonfun$cleanUpAfterSchedulerStop$1.apply(DAGScheduler.scala:808)
17/07/11 14:15:32 INFO DAGScheduler: ShuffleMapStage 1 (map at stack.scala:85) failed in 294.165 s due to Stage cancelled because SparkContext was shut down
17/07/11 14:15:32 ERROR LiveListenerBus: SparkListenerBus has already stopped! Dropping event SparkListenerStageCompleted(org.apache.spark.scheduler.StageInfo@cfb906)
17/07/11 14:15:32 ERROR LiveListenerBus: SparkListenerBus has already stopped! Dropping event SparkListenerJobEnd(0,1499762732342,JobFailed(org.apache.spark.SparkException: Job 0 cancelled because SparkContext was shut down))
17/07/11 14:15:32 ERROR SparkUncaughtExceptionHandler: [Container in shutdown] Uncaught exception in thread Thread[Executor task launch worker-1,5,main]
java.lang.OutOfMemoryError: GC overhead limit exceeded
17/07/11 14:15:32 INFO DiskBlockManager: Shutdown hook called
17/07/11 14:15:32 INFO MapOutputTrackerMasterEndpoint: MapOutputTrackerMasterEndpoint stopped!
17/07/11 14:15:32 INFO ShutdownHookManager: Shutdown hook called
17/07/11 14:15:32 INFO MemoryStore: MemoryStore cleared
17/07/11 14:15:32 INFO BlockManager: BlockManager stopped
17/07/11 14:15:32 INFO BlockManagerMaster: BlockManagerMaster stopped
17/07/11 14:15:32 INFO ShutdownHookManager: Deleting directory /tmp/spark-0b2ea8bd-95c0-45e4-a1cc-bd62b3899b24
17/07/11 14:15:32 INFO ShutdownHookManager: Deleting directory /tmp/spark-0b2ea8bd-95c0-45e4-a1cc-bd62b3899b24/userFiles-194d73ba-fcfa-4616-ae17-78b0bba6b465
17/07/11 14:15:32 INFO OutputCommitCoordinator$OutputCommitCoordinatorEndpoint: OutputCommitCoordinator stopped!

Spark Configurations

我正在使用 2g 内存和 1 个内核执行，尽管它处于开发模式。我是新来的，对不起这样一个幼稚的问题。

谢谢。！

首先，您正在启动两个SparkSession，这是毫无用处的，您只是在拆分资源。所以不要那样做！

其次，这就是问题所在。关于Apache Spark的并行性和jdbc源代码存在误解(别担心，这是一个陷阱！

这主要是由于缺少文档。(我上次检查过(

所以回到问题。实际发生的是以下行：

val destination = spark.read.jdbc(url, queryDestination, connectionProperties).rdd.map(_.mkString(","))

是它将读取委托给单个工作线程。

所以主要是，如果你有足够的内存并且你成功地读取了这些数据。整个destination数据将位于一个分区中。一个分区意味着麻烦！又名可能：

java.lang.OutOfMemoryError: GC overhead limit exceeded

所以发生的事情是，被选择获取数据的单个执行器不堪重负，它的JVM爆炸了。

现在让我们解决这个问题：

(免责声明：以下代码是spark-gotchas的摘录，我是它的作者之一。

因此，让我们创建一些示例数据并将它们保存在我们的数据库中：

val options = Map(
"url" -> "jdbc:postgresql://127.0.0.1:5432/spark",
"dbtable" -> "data",
"driver" -> "org.postgresql.Driver",
"user" -> "spark",
"password" -> "spark"
)
val newData = spark.range(1000000)
.select($"id", lit(""), lit(true), current_timestamp())
.toDF("id", "name", "valid", "ts")
newData.write.format("jdbc").options(options).mode("append").save

Apache Spark提供了两种方法，用于通过JDBC进行分布式数据加载。第一个使用整数列对数据进行分区：

val dfPartitionedWithRanges = spark.read.options(options)
.jdbc(options("url"), options("dbtable"), "id", 1, 5, 4, new java.util.Properties())
dfPartitionedWithRanges.rdd.partitions.size
// Int = 4
dfPartitionedWithRanges.rdd.glom.collect
// Array[Array[org.apache.spark.sql.Row]] = Array(
//   Array([1,foo,true,2012-01-01 00:03:00.0]),
//   Array([2,foo,false,2013-04-02 10:10:00.0]),
//   Array([3,bar,true,2015-11-02 22:00:00.0]),
//   Array([4,bar,false,2010-11-02 22:00:00.0]))
Partition column and bounds can provided using options as well:
val optionsWithBounds = options ++ Map(
"partitionColumn" -> "id",
"lowerBound" -> "1",
"upperBound" -> "5",
"numPartitions" -> "4"
)
spark.read.options(optionsWithBounds).format("jdbc").load

分区列和边界也可以使用选项提供：

val optionsWithBounds = options ++ Map(
"partitionColumn" -> "id",
"lowerBound" -> "1",
"upperBound" -> "5",
"numPartitions" -> "4"
)
spark.read.options(optionsWithBounds).format("jdbc").load

另一种选择是使用一系列谓词，但我不会在这里谈论它。

您可以在此处阅读有关Spark SQL和JDBC源代码的更多信息以及其他一些陷阱。

我希望这有所帮助。

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