火花引發的OutOfMemoryError

Question

當我如下運行我的火花Python代碼：

import pyspark 
conf = (pyspark.SparkConf() 
    .setMaster("local") 
    .setAppName("My app") 
    .set("spark.executor.memory", "512m")) 
sc = pyspark.SparkContext(conf = conf)  #start the conf 
data =sc.textFile('/Users/tsangbosco/Downloads/transactions') 
data = data.flatMap(lambda x:x.split()).take(all) 

文件大小約爲20G和我的電腦有8G的內存，當我以單機模式運行程序時，它引發的OutOfMemoryError：

Exception in thread "Local computation of job 12" java.lang.OutOfMemoryError: Java heap space 
    at org.apache.spark.api.python.PythonRDD$$anon$1.read(PythonRDD.scala:131) 
    at org.apache.spark.api.python.PythonRDD$$anon$1.next(PythonRDD.scala:119) 
    at org.apache.spark.api.python.PythonRDD$$anon$1.next(PythonRDD.scala:112) 
    at scala.collection.Iterator$class.foreach(Iterator.scala:727) 
    at org.apache.spark.api.python.PythonRDD$$anon$1.foreach(PythonRDD.scala:112) 
    at scala.collection.generic.Growable$class.$plus$plus$eq(Growable.scala:48) 
    at scala.collection.mutable.ArrayBuffer.$plus$plus$eq(ArrayBuffer.scala:103) 
    at scala.collection.mutable.ArrayBuffer.$plus$plus$eq(ArrayBuffer.scala:47) 
    at scala.collection.TraversableOnce$class.to(TraversableOnce.scala:273) 
    at org.apache.spark.api.python.PythonRDD$$anon$1.to(PythonRDD.scala:112) 
    at scala.collection.TraversableOnce$class.toBuffer(TraversableOnce.scala:265) 
    at org.apache.spark.api.python.PythonRDD$$anon$1.toBuffer(PythonRDD.scala:112) 
    at scala.collection.TraversableOnce$class.toArray(TraversableOnce.scala:252) 
    at org.apache.spark.api.python.PythonRDD$$anon$1.toArray(PythonRDD.scala:112) 
    at org.apache.spark.api.java.JavaRDDLike$$anonfun$1.apply(JavaRDDLike.scala:259) 
    at org.apache.spark.api.java.JavaRDDLike$$anonfun$1.apply(JavaRDDLike.scala:259) 
    at org.apache.spark.SparkContext$$anonfun$runJob$4.apply(SparkContext.scala:884) 
    at org.apache.spark.SparkContext$$anonfun$runJob$4.apply(SparkContext.scala:884) 
    at org.apache.spark.scheduler.DAGScheduler.runLocallyWithinThread(DAGScheduler.scala:681) 
    at org.apache.spark.scheduler.DAGScheduler$$anon$1.run(DAGScheduler.scala:666) 

火花無法處理大於我的內存的文件？你能告訴我如何解決它？

Answer 1

Spark可以處理某些情況。但是您使用take強制Spark將所有數據提取到數組（在內存中）。在這種情況下，您應該將它們存儲到文件中，例如使用saveAsTextFile。

如果您有興趣查看部分數據，可以使用sample或takeSample。