Getting the Tool Interface warning even though it is implemented

问题

I have a very simple "Hello world" style map/reduce job.

public class Tester extends Configured implements Tool {

    @Override
    public int run(String[] args) throws Exception {
        if (args.length != 2) {
            System.err.printf("Usage: %s [generic options] <input> <output>\n",
                getClass().getSimpleName());
            ToolRunner.printGenericCommandUsage(System.err);
            return -1;
        }

        Job job = Job.getInstance(new Configuration());
        job.setJarByClass(getClass());


        getConf().set("mapreduce.job.queuename", "adhoc");

        FileInputFormat.addInputPath(job, new Path(args[0]));
        FileOutputFormat.setOutputPath(job, new Path(args[1]));

        job.setOutputKeyClass(Text.class);
        job.setOutputValueClass(NullWritable.class);
        job.setMapperClass(TesterMapper.class);
        job.setNumReduceTasks(0);

        return job.waitForCompletion(true) ? 0 : 1;
    }

    public static void main(String[] args) throws Exception {
        int exitCode = ToolRunner.run(new Tester(), args);
        System.exit(exitCode);
    }

Which implements the ToolRunner, but when run is not parsing the arguments.

$hadoop jar target/manifold-mapreduce-0.1.0.jar ga.manifold.mapreduce.Tester -conf conf.xml etl/manifold/pipeline/ABV1T/ingest/input etl/manifold/pipeline/ABV1T/ingest/output
15/02/04 16:35:24 INFO client.RMProxy: Connecting to ResourceManager at lxjh116-pvt.phibred.com/10.56.100.23:8050
15/02/04 16:35:25 WARN mapreduce.JobSubmitter: Hadoop command-line option parsing not performed. Implement the Tool interface and execute your application with ToolRunner to remedy this.

I can verify that the configuration is not being added.

Anyone know why Hadoop thinks the ToolRunner isn't implemented?

$hadoop version Hadoop 2.4.0.2.1.2.0-402

Hortonworks

Thanks, Chris

回答1:

As your question pops really fast on the top of Google search for this warning, I'll give a proper answer here :

As ~~user1797538~~ you said : (sorry about that)

user1797538: "The problem was the call to get a Job instance"

The superclass Configured must be used. As its name suggests, it is already configured, so the existing Configuration must be used by the Tester class and not set a new empty one.

If we extract the Job creation in a method :

private Job createJob() throws IOException {

    // On this line use getConf() instead of new Configuration()
    Job job = Job.getInstance(getConf(), Tester.class.getCanonicalName());

    // Other job setter call here, for example
    job.setJarByClass(Tester.class);
    job.setMapperClass(TesterMapper.class);
    job.setCombinerClass(TesterReducer.class);
    job.setReducerClass(TesterReducer.class);
    job.setOutputKeyClass(Text.class);
    job.setOutputValueClass(IntWritable.class);
    // adapt this to your needs of course.

    return job;
}

Another example from the javadoc : org.apache.hadoop.util.Tool

And the Javadoc : Configured.getConf()

来源：https://stackoverflow.com/questions/28333080/getting-the-tool-interface-warning-even-though-it-is-implemented

标签

java

Hadoop

MapReduce

hortonworks-data-platform