hbase-user mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Ted Yu <yuzhih...@gmail.com>
Subject Re: M/R scan problem
Date Mon, 04 Jul 2011 14:55:25 GMT
For #2, see 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.


On Mon, Jul 4, 2011 at 7:37 AM, Lior Schachter <liors@infolinks.com> wrote:

> 1. yes - I configure my job using this line:
> TableMapReduceUtil.initTableMapperJob(HBaseConsts.URLS_TABLE_NAME, scan,
> ScanMapper.class, Text.class, MapWritable.class, job)
>
> which internally uses TableInputFormat.class
>
> 2. One split per region ? What do you mean ? How do I do that ?
>
> 3. hbase version 0.90.2
>
> 4. no exceptions. the logs are very clean.
>
>
>
> On Mon, Jul 4, 2011 at 5:22 PM, Ted Yu <yuzhihong@gmail.com> wrote:
>
> > Do you use TableInputFormat ?
> > To scan large number of rows, it would be better to produce one Split per
> > region.
> >
> > What HBase version do you use ?
> > Do you find any exception in master / region server logs around the
> moment
> > of timeout ?
> >
> > Cheers
> >
> > On Mon, Jul 4, 2011 at 4:48 AM, Lior Schachter <liors@infolinks.com>
> > wrote:
> >
> > > Hi all,
> > > I'm running a scan using the M/R framework.
> > > My table contains hundreds of millions of rows and I'm scanning using
> > > start/stop key about 50 million rows.
> > >
> > > The problem is that some map tasks get stuck and the task manager kills
> > > these maps after 600 seconds. When retrying the task everything works
> > fine
> > > (sometimes).
> > >
> > > To verify that the problem is in hbase (and not in the map code) I
> > removed
> > > all the code from my map function, so it looks like this:
> > > public void map(ImmutableBytesWritable key, Result value, Context
> > context)
> > > throws IOException, InterruptedException {
> > > }
> > >
> > > Also, when the map got stuck on a region, I tried to scan this region
> > > (using
> > > simple scan from a Java main) and it worked fine.
> > >
> > > Any ideas ?
> > >
> > > Thanks,
> > > Lior
> > >
> >
>

Mime
  • Unnamed multipart/alternative (inline, None, 0 bytes)
View raw message