Thanks Ted,
Finally I found the real mistake, the class had to be declared static.
Best,
Iván.
----- Mensaje original -----
> De: "Ted Yu" <yuzhih...@gmail.com>
> Para: user@hbase.apache.org
> Enviados: Martes, 19 de Abril 2016 15:56:56
> Asunto: Re: Processing rows in parallel with MapReduce jobs.
>
> From the error, you need to provide an argumentless ctor for
> MyTableInputFormat.
>
> On Tue, Apr 19, 2016 at 12:12 AM, Ivan Cores gonzalez <ivan.co...@inria.fr>
> wrote:
>
> >
> > Hi Ted,
> >
> > Sorry, I forgot to write the error. In runtime I have the next exception:
> >
> > Exception in thread "main" java.lang.RuntimeException:
> > java.lang.NoSuchMethodException:
> > simplerowcounter.SimpleRowCounter$MyTableInputFormat.<init>()
> >
> > the program works fine if I don't use "MyTableInputFormat" modifying the
> > call to initTableMapperJob:
> >
> > TableMapReduceUtil.initTableMapperJob(tableName, scan,
> > RowCounterMapper.class,
> > ImmutableBytesWritable.class, Result.class, job); // -->
> > works fine without MyTableInputFormat
> >
> > That's why I asked If you see any problem in the code. Because maybe I
> > forgot override some method or something is missing.
> >
> > Best,
> > Iván.
> >
> >
> > ----- Mensaje original -----
> > > De: "Ted Yu" <yuzhih...@gmail.com>
> > > Para: user@hbase.apache.org
> > > Enviados: Martes, 19 de Abril 2016 0:22:05
> > > Asunto: Re: Processing rows in parallel with MapReduce jobs.
> > >
> > > 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.
> > > > > > > >
> > > > > > >
> > > > > >
> > > > >
> > > >
> > >
> >
>
