Apache Pig:OutOfMemory异常，在本地模式下具有简单的GROUP BY [英] Apache Pig: OutOfMemory exception with simple GROUP BY in local mode

问题描述

当我尝试在一个很小的(3KB)随机生成的示例数据集上执行一个非常简单的GROUP BY时，我从Pig收到了OutOfMemory异常.

I'm getting an OutOfMemory exception from Pig when trying to execute a very simple GROUP BY on a tiny (3KB), randomly-generated, example data set.

猪脚本:

$ cat example.pig
raw =
LOAD 'example-data'
    USING PigStorage()
    AS (thing1_id:int,
        thing2_id:int,
        name:chararray,
        timestamp:long);

grouped =
GROUP raw BY thing1_id;

DUMP grouped;

数据:

$ cat example-data
281906  13636091    hide    1334350350
174952  20148444    save    1334427826
1082780 16033108    hide    1334500374
2932953 14682185    save    1334501648
1908385 28928536    hide    1334367665
[snip]

$ wc example-data
 100  400 3239 example-data

我们在这里:

$ pig -x local example.pig

[snip]

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)

[snip]

以及一些其他信息:

$ apt-cache show hadoop | grep Version
Version: 1.0.2

$ pig --version
Apache Pig version 0.9.2 (r1232772) 
compiled Jan 17 2012, 23:49:20

$ echo $PIG_HEAPSIZE
4096

在这一点上，我觉得我必须做一些严重的错误，因为我看不到任何原因导致3 kB的文本会导致堆被填满.

At this point, I feel like I must be doing something drastically wrong because I can't see any reason why 3 kB of text would ever cause the heap to fill up.

推荐答案

检查此内容:[链接]

Check this: [link] http://sumedha.blogspot.in/2012/01/solving-apache-pig-javalangoutofmemorye.html

尼尔，你是对的，让我解释一下这样的事情:在bin/pig脚本文件中，源代码是:

neil, you are right, let me explain the things like this: In the bin/pig script file, the source code is :

JAVA_HEAP_MAX = -Xmx1000m

JAVA_HEAP_MAX=-Xmx1000m

#检查可能覆盖默认参数的envvars

# check envvars which might override default args

如果[["$ PIG_HEAPSIZE"！="];然后 JAVA_HEAP_MAX =-Xmx""$ PIG_HEAPSIZE""m" fi

if [ "$PIG_HEAPSIZE" != "" ]; then JAVA_HEAP_MAX="-Xmx""$PIG_HEAPSIZE""m" fi

仅使用-Xmx开关将Java_heap_size设置为maxium("x")，但是我不知道为什么此脚本覆盖无效，这是原因，我要求您使用以下命令直接指定Java堆大小链接中指定的参数.我没有时间检查为什么这个问题引发了.如果有任何想法，请在此处发布.

It is setting the Java_heap_size to maxium ("x") using the -Xmx switch only,but i didnot know why this script overriding is not working, that is the reason, i asked you to specify directly the java heap size using the paramters as specified in the link. I didnot got time to check why this problem is raising. If any one have idea please post it here.

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