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How to set mapreduce.input.fileinputformat.split.maxsize for a specific job ?

+1 vote
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In xmls configuration file of Hadoop-2.x, "mapreduce.input.fileinputformat.split.minsize" is given which can be set but how to set "mapreduce.input.fileinputformat.split.maxsize" in xml file. I need to set it in my mapreduce code.

posted May 16, 2015 by Sudhakar Singh

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1 Answer

+2 votes

You can either pass them on as command line argument using -D option. Assuming your job is implementing the standard Tool interface:
https://hadoop.apache.org/docs/current/api/org/apache/hadoop/util/Tool.html

Or you can set them in the code using the various 'set' methods to set key/value values in the configuration object.

...
Job job = Job.getInstance(getConf());
job.setJarByClass(MyJob.class);

job.getConfiguration().set("<property-name>",<value>);
....

Docs for Configuration class:
https://hadoop.apache.org/docs/current/api/org/apache/hadoop/conf/Configuration.html

This will work as long as the property is not marked final

answer May 16, 2015 by anonymous
Thanks, Is this the correct way to write ?
conf.set("mapreduce.input.fileinputformat.split.maxsize", "102400");
or
job.getConfiguration().set("mapreduce.input.fileinputformat.split.maxsize", "102400");

I think another ways as
FileInputFormat.setMaxInputSplitSize(null, 102400);

Is this all right ? Are these both solve the same purpose or something else ?
What do you think is  the type of the property value that you are trying to write? Is it string? Or numeric? Have you check the documentation of the Configuration class that I sent earlier?

There are multiple setXXX methods depending on the type of the property value being set:
https://hadoop.apache.org/docs/current/api/org/apache/hadoop/conf/Configuration.html #setLong(java.lang.String, long)


For the other case below, why are you setting the job object (first parameter) as null?
FileInputFormat.setMaxInputSplitSize(null, 102400);
Check out the documentation here:
http://hadoop.apache.org/docs/r2.4.1/api/org/apache/hadoop/mapreduce/lib/input/FileInputFormat.html #setMaxInputSplitSize(org.apache.hadoop.mapreduce.Job, long)

Lastly,
 conf.set("mapreduce.input.fileinputformat.split.maxsize", "102400");
VS.
job.getConfiguration().set("mapreduce.input.fileinputformat.split.maxsize", "102400");
is just a matter of how you are referencing the configuration object. Either as its own reference of through chained called from the job object. That is programming style decision and has no bearing on it.
Thanks a lot.
Sorry that was not null, but typed unintentionally. So I can use one of the following.
conf.setLong("mapreduce.input.fileinputformat.split.maxsize", 102400);
or
FileInputFormat.setMaxInputSplitSize(job, 102400);
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public class MaxMinReducer extends Reducer {
int max_sum=0; 
int mean=0;
int count=0;
Text max_occured_key=new Text();
Text mean_key=new Text("Mean : ");
Text count_key=new Text("Count : ");
int min_sum=Integer.MAX_VALUE; 
Text min_occured_key=new Text();

 public void reduce(Text key, Iterable<IntWritable> values, Context context) throws IOException, InterruptedException {
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       for (IntWritable value : values) {
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 @Override
 protected void cleanup(Context context) throws IOException, InterruptedException {
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Here I am writing minimum,maximum and mean of wordcount.

My input file :

high low medium high low high low large small medium

Actual output is :

high - 3------maximum

low - 3--------maximum

large - 1------minimum

small - 1------minimum

but i am not getting above output ...can anyone please help me?

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