Pig 本地模式、组或加入 = java.lang.OutOfMemoryError: Java 堆空间 [英] Pig local mode, group, or join = java.lang.OutOfMemoryError: Java heap space

问题描述

使用 Apache Pig 版本 0.10.1.21(报告)，CentOS 版本 6.3(最终版)，jdk1.6.0_31(Virtualbox 上的 Hortonworks Sandbox v1.2，具有 3.5 GB RAM)

Using Apache Pig version 0.10.1.21 (reported), CentOS release 6.3 (Final), jdk1.6.0_31 (The Hortonworks Sandbox v1.2 on Virtualbox, with 3.5 GB RAM)

$ cat data.txt
11,11,22
33,34,35
47,0,21
33,6,51
56,6,11
11,25,67

$ cat GrpTest.pig
A = LOAD 'data.txt' USING PigStorage(',') AS (f1:int,f2:int,f3:int);
B = GROUP A BY f1;
DESCRIBE B;
DUMP B;

pig -x local GrpTest.pig

[Thread-12] WARN  org.apache.hadoop.mapred.JobClient - No job jar file set.  User classes may not be found. See JobConf(Class) or JobConf#setJar(String).
[Thread-12] INFO  org.apache.hadoop.mapreduce.lib.input.FileInputFormat - Total input paths to process : 1
[Thread-13] INFO  org.apache.hadoop.mapred.Task -  Using ResourceCalculatorPlugin : org.apache.hadoop.util.LinuxResourceCalculatorPlugin@19a9bea3
[Thread-13] INFO  org.apache.hadoop.mapred.MapTask - io.sort.mb = 100
[Thread-13] WARN  org.apache.hadoop.mapred.LocalJobRunner - job_local_0002
java.lang.OutOfMemoryError: Java heap space
    at org.apache.hadoop.mapred.MapTask$MapOutputBuffer.<init>(MapTask.java:949)
    at org.apache.hadoop.mapred.MapTask$NewOutputCollector.<init>(MapTask.java:674)
    at org.apache.hadoop.mapred.MapTask.runNewMapper(MapTask.java:756)
    at org.apache.hadoop.mapred.MapTask.run(MapTask.java:370)
    at org.apache.hadoop.mapred.LocalJobRunner$Job.run(LocalJobRunner.java:212)
[main] ERROR org.apache.pig.tools.pigstats.PigStatsUtil - 1 map reduce job(s) failed!
[main] ERROR org.apache.pig.tools.grunt.Grunt - ERROR 1066: Unable to open iterator for alias B

java.lang.OutOfMemoryError: Java heap space 每次我在本地模式下执行的 pig 脚本中使用 GROUP 或 JOIN 时都会发生错误.HDFS上mapreduce模式执行脚本没有报错.

The java.lang.OutOfMemoryError: Java heap space error occurs each time I use GROUP or JOIN in a pig script executed in local mode. There is no error when the script is executed in mapreduce mode on HDFS.

问题 1:为什么会出现 OutOfMemory 错误，而数据样本很小，而且本地模式应该比 HDFS 模式使用更少的资源?

Question 1: How come there is an OutOfMemory error while the data sample is minuscule and local mode is supposed to use less resources than HDFS mode?

问题 2:有没有办法在本地模式下使用 GROUP 或 JOIN 成功运行小猪脚本?

Question 2: Is there a solution to run successfully a small pig scripts with GROUP or JOIN in local mode?

推荐答案

解决方案:强制 pig 为 java 属性 io.sort.mb 分配更少的内存我在这里设置为 10 MB，错误消失了.不确定什么是最好的价值，但至少，这允许在本地模式下练习猪语法

Solution: force pig to allocate less memory for the java property io.sort.mb I set to 10 MB here and the error disappears. Not sure what would be the best value but at least, this allow to practice pig syntax in local mode

$ cat GrpTest.pig
--avoid java.lang.OutOfMemoryError: Java heap space (execmode: -x local)
set io.sort.mb 10;

A = LOAD 'data.txt' USING PigStorage(',') AS (f1:int,f2:int,f3:int);
B = GROUP A BY f1;
DESCRIBE B;
DUMP B;

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