Did you see the " Message to log?" log ?
Can you pastebin the error / exception you got ?
On Mon, Apr 18, 2016 at 1:54 AM, Ivan Cores gonzalez <ivan.co...@inria.fr>
wrote:
>
>
> Hi Ted,
> So, If I understand the behaviour of getSplits(), I can create "virtual"
> splits overriding the getSplits function.
> I was performing some tests, but my code crash in runtime and I cannot
> found the problem.
> Any help? I didn't find examples.
>
>
> public class SimpleRowCounter extends Configured implements Tool {
>
> static class RowCounterMapper extends
> TableMapper<ImmutableBytesWritable, Result> {
> public static enum Counters { ROWS }
> @Override
> public void map(ImmutableBytesWritable row, Result value, Context
> context) {
> context.getCounter(Counters.ROWS).increment(1);
> try {
> Thread.sleep(3000); //Simulates work
> } catch (InterruptedException name) { }
> }
> }
>
> public class MyTableInputFormat extends TableInputFormat {
> @Override
> public List<InputSplit> getSplits(JobContext context) throws
> IOException {
> //Just to detect if this method is being called ...
> List<InputSplit> splits = super.getSplits(context);
> System.out.printf(" Message to log? \n" );
> return splits;
> }
> }
>
> @Override
> public int run(String[] args) throws Exception {
> if (args.length != 1) {
> System.err.println("Usage: SimpleRowCounter <tablename>");
> return -1;
> }
> String tableName = args[0];
>
> Scan scan = new Scan();
> scan.setFilter(new FirstKeyOnlyFilter());
> scan.setCaching(500);
> scan.setCacheBlocks(false);
>
> Job job = new Job(getConf(), getClass().getSimpleName());
> job.setJarByClass(getClass());
>
> TableMapReduceUtil.initTableMapperJob(tableName, scan,
> RowCounterMapper.class,
> ImmutableBytesWritable.class, Result.class, job, true,
> MyTableInputFormat.class);
>
> job.setNumReduceTasks(0);
> job.setOutputFormatClass(NullOutputFormat.class);
> return job.waitForCompletion(true) ? 0 : 1;
> }
>
> public static void main(String[] args) throws Exception {
> int exitCode = ToolRunner.run(HBaseConfiguration.create(),
> new SimpleRowCounter(), args);
> System.exit(exitCode);
> }
> }
>
> Thanks so much,
> Iván.
>
>
>
>
> ----- Mensaje original -----
> > De: "Ted Yu" <yuzhih...@gmail.com>
> > Para: user@hbase.apache.org
> > Enviados: Martes, 12 de Abril 2016 17:29:52
> > Asunto: Re: Processing rows in parallel with MapReduce jobs.
> >
> > Please take a look at TableInputFormatBase#getSplits() :
> >
> > * Calculates the splits that will serve as input for the map tasks.
> The
> >
> > * number of splits matches the number of regions in a table.
> >
> > Each mapper would be reading one of the regions.
> >
> > On Tue, Apr 12, 2016 at 8:18 AM, Ivan Cores gonzalez <
> ivan.co...@inria.fr>
> > wrote:
> >
> > > Hi Ted,
> > > Yes, I mean same region.
> > >
> > > I wasn't using the getSplits() function. I'm trying to add it to my
> code
> > > but I'm not sure how I have to do it. Is there any example in the
> website?
> > > I can not find anything. (By the way, I'm using TableInputFormat, not
> > > InputFormat)
> > >
> > > But just to confirm, with the getSplits() function, Are mappers
> processing
> > > rows in the same region executed in parallel? (assuming that there are
> > > empty
> > > processors/cores)
> > >
> > > Thanks,
> > > Ivan.
> > >
> > >
> > > ----- Mensaje original -----
> > > > De: "Ted Yu" <yuzhih...@gmail.com>
> > > > Para: user@hbase.apache.org
> > > > Enviados: Lunes, 11 de Abril 2016 15:10:29
> > > > Asunto: Re: Processing rows in parallel with MapReduce jobs.
> > > >
> > > > bq. if they are located in the same split?
> > > >
> > > > Probably you meant same region.
> > > >
> > > > Can you show the getSplits() for the InputFormat of your MapReduce
> job ?
> > > >
> > > > Thanks
> > > >
> > > > On Mon, Apr 11, 2016 at 5:48 AM, Ivan Cores gonzalez <
> > > ivan.co...@inria.fr>
> > > > wrote:
> > > >
> > > > > Hi all,
> > > > >
> > > > > I have a small question regarding the MapReduce jobs behaviour with
> > > HBase.
> > > > >
> > > > > I have a HBase test table with only 8 rows. I splitted the table
> with
> > > the
> > > > > hbase shell
> > > > > split command into 2 splits. So now there are 4 rows in every
> split.
> > > > >
> > > > > I create a MapReduce job that only prints the row key in the log
> files.
> > > > > When I run the MapReduce job, every row is processed by 1 mapper.
> But
> > > the
> > > > > mappers
> > > > > in the same split are executed sequentially (inside the same
> > > container).
> > > > > That means,
> > > > > the first four rows are processed sequentially by 4 mappers. The
> system
> > > > > has cores
> > > > > that are free, so is it possible to process rows in parallel if
> they
> > > are
> > > > > located
> > > > > in the same split?
> > > > >
> > > > > The only way I found to have 8 mappers executed in parallel is
> split
> > > the
> > > > > table
> > > > > in 8 splits (1 split per row). But obviously this is not the best
> > > solution
> > > > > for
> > > > > big tables ...
> > > > >
> > > > > Thanks,
> > > > > Ivan.
> > > > >
> > > >
> > >
> >
>
