In fact, on close() of the HadoopOutputFormat the fileOutputCommitter returns false on if (this.fileOutputCommitter.needsTaskCommit(this.context)) returns false.

i    /**
     * commit the task by moving the output file out from the temporary directory.
     * @throws java.io.IOException
     */
    @Override
    public void close() throws IOException {
        this.recordWriter.close(new HadoopDummyReporter());
       
        if (this.fileOutputCommitter.needsTaskCommit(this.context)) {
            this.fileOutputCommitter.commitTask(this.context);
        }
    }


Also, both the close and the finalize global use a FileOutputCommitter, and never the MongoOutputCommitter

@Override
    public void finalizeGlobal(int parallelism) throws IOException {

        try {
            JobContext jobContext = HadoopUtils.instantiateJobContext(this.jobConf, new JobID());
            FileOutputCommitter fileOutputCommitter = new FileOutputCommitter();
           
            // finalize HDFS output format
            fileOutputCommitter.commitJob(jobContext);
        } catch (Exception e) {
            throw new RuntimeException(e);
        }
    }

anyone can have a look into that?

saluti,
Stefano

2015-07-22 15:53 GMT+02:00 Stefano Bortoli <bortoli@okkam.it>:
Debugging, it seem the commitTask method of the MongoOutputCommitter is never called. Is it possible that this 'bulk' approach of mongo-hadoop 1.4 does not fit the task execution method of Flink?

any idea? thanks a lot in advance.

saluti,
Stefano

Stefano Bortoli, PhD
ENS Technical Director
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2015-07-22 14:26 GMT+02:00 Stefano Bortoli <s.bortoli@gmail.com>:
Hi,

I am trying to analyze and update a MongoDB collection with Apache Flink 0.9.0 and Mongo Hadoop 1.4.0 Hadoop 2.6.0.

The process is fairly simple, and the MongoInputFormat works smoothly, however it does not write back to the collection. The process works, because the writeAsText works as expected. I am quite puzzled because debugging I can see it writes in some temporary directory.

The mapred.output.uri seem to serve just to output a file named  _SUCCESS, and if I do not set it fails with
java.lang.IllegalArgumentException: Can not create a Path from a null string
    at org.apache.hadoop.fs.Path.checkPathArg(Path.java:123)
    at org.apache.hadoop.fs.Path.<init>(Path.java:135)
    at org.apache.flink.api.java.hadoop.mapreduce.HadoopOutputFormatBase.open(HadoopOutputFormatBase.java:108)
    at org.apache.flink.runtime.operators.DataSinkTask.invoke(DataSinkTask.java:186)
    at org.apache.flink.runtime.taskmanager.Task.run(Task.java:559)
    at java.lang.Thread.run(Thread.java:745)

Anyone experienced something similar? any hints where to look at? Thanks a lot in advance!

saluti,
Stefano

====================================================
Configuration conf = new Configuration();
conf.set("mapred.output.dir", "/tmp/");
        conf.set(MongoUtil.MONGO_INPUT_URI_PROPERTY,
                collectionsUri);
        conf.set(MongoUtil.MONGO_OUTPUT_URI_PROPERTY,
                collectionsUri);
            
        Job job = Job.getInstance(conf);
        
        // create a MongodbInputFormat, using a Hadoop input format wrapper
        InputFormat<Object, BSONObject>  mapreduceInputFormat =  new MyMongoInputFormat<Object, BSONObject>();
        HadoopInputFormat<Object, BSONObject> hdIf = new HadoopInputFormat<Object, BSONObject>(
                mapreduceInputFormat, Object.class, BSONObject.class,
                job);
DataSet<Tuple2<Text, BSONWritable>> fin = input
                .flatMap(new myFlatMapFunction()).setParallelism(16);

        MongoConfigUtil.setOutputURI(job.getConfiguration(), collectionsUri);

        fin.output(new HadoopOutputFormat<Text, BSONWritable>(
                new MongoOutputFormat<Text, BSONWritable>(),
                job));
//        fin.writeAsText("/tmp/out", WriteMode.OVERWRITE);