I was thinking something like this:
Scan scan = new Scan(startRow, endRow);
scan.setCaching(someVal); // based on what we expect most rows to take for
processing time
ResultScanner scanner = table.getScanner(scan);
for (Result r : scanner) {
// usual processing, the time for which we accounted for in our caching
and global lease timeout settings
if (someCondition) {
// More time-intensive processing necessary on this record, which is
hard to account for in the caching
scanner.progress();
}
}
--
I'm not sure how we could expose this in the context of a hadoop job, since
I don't believe we have access to the underlying scanner, but that would be
great also.
On Wed, Mar 20, 2013 at 1:11 PM, Ted Yu <[email protected]> wrote:
> bq. if HBase provided a way to manually refresh a lease similar to
> Hadoop's context.progress()
>
> Can you outline how the above works for long scan ?
>
> bq. Even being able to override the timeout on a per-scan basis would be
> nice.
>
> Agreed.
>
> On Wed, Mar 20, 2013 at 10:05 AM, Bryan Beaudreault <
> [email protected]> wrote:
>
> > Typically it is better to use caching and batch size to limit the number
> of
> > rows returned and thus the amount of processing required between calls to
> > next() during a scan, but it would be nice if HBase provided a way to
> > manually refresh a lease similar to Hadoop's context.progress(). In a
> > cluster that is used for many different applications, upping the global
> > lease timeout is a heavy handed solution. Even being able to override
> the
> > timeout on a per-scan basis would be nice.
> >
> > Thoughts on that, Ted?
> >
> >
> > On Wed, Mar 20, 2013 at 1:00 PM, Ted Yu <[email protected]> wrote:
> >
> > > In 0.94, there is only one setting.
> > > See release notes of HBASE-6170 which is in 0.95
> > >
> > > Looks like this should help (in 0.95):
> > >
> > > https://issues.apache.org/jira/browse/HBASE-2214
> > > Do HBASE-1996 -- setting size to return in scan rather than count of
> rows
> > > -- properly
> > >
> > > From your description, you should be able to raise the timeout since
> the
> > > writes are relatively fast.
> > >
> > > Cheers
> > >
> > > On Wed, Mar 20, 2013 at 9:32 AM, Dan Crosta <[email protected]> wrote:
> > >
> > > > I'm confused -- I only see one setting in CDH manager, what is the
> name
> > > of
> > > > the other setting?
> > > >
> > > > Our load is moderately frequent small writes (in batches of 1000
> cells
> > at
> > > > a time, typically split over a few hundred rows -- these complete
> very
> > > > fast, we haven't seen any timeouts there), and infrequent batches of
> > > large
> > > > reads (scans), which is where we do see timeouts. My guess is that
> the
> > > > timeout is more due to our application taking some time -- apparently
> > > more
> > > > than 60s -- to process the results of each scan's output, rather than
> > due
> > > > to slowness in HBase itself, which tends to be only moderately loaded
> > > > (judging by CPU, network, and disk) while we do the reads.
> > > >
> > > > Thanks,
> > > > - Dan
> > > >
> > > > On Mar 17, 2013, at 2:20 PM, Ted Yu wrote:
> > > >
> > > > > The lease timeout is used by row locking too.
> > > > > That's the reason behind splitting the setting into two config
> > > > parameters.
> > > > >
> > > > > How is your load composition ? Do you mostly serve reads from
> HBase ?
> > > > >
> > > > > Cheers
> > > > >
> > > > > On Sun, Mar 17, 2013 at 1:56 PM, Dan Crosta <[email protected]>
> > wrote:
> > > > >
> > > > >> Ah, thanks Ted -- I was wondering what that setting was for.
> > > > >>
> > > > >> We are using CDH 4.2.0, which is HBase 0.94.2 (give or take a few
> > > > >> backports from 0.94.3).
> > > > >>
> > > > >> Is there any harm in setting the lease timeout to something
> larger,
> > > > like 5
> > > > >> or 10 minutes?
> > > > >>
> > > > >> Thanks,
> > > > >> - Dan
> > > > >>
> > > > >> On Mar 17, 2013, at 1:46 PM, Ted Yu wrote:
> > > > >>
> > > > >>> Which HBase version are you using ?
> > > > >>>
> > > > >>> In 0.94 and prior, the config param is
> > > hbase.regionserver.lease.period
> > > > >>>
> > > > >>> In 0.95, it is different. See release notes of HBASE-6170
> > > > >>>
> > > > >>> On Sun, Mar 17, 2013 at 11:46 AM, Dan Crosta <[email protected]>
> > > wrote:
> > > > >>>
> > > > >>>> We occasionally get scanner timeout errors such as "66698ms
> passed
> > > > since
> > > > >>>> the last invocation, timeout is currently set to 60000" when
> > > > iterating a
> > > > >>>> scanner through the Thrift API. Is there any reason not to raise
> > the
> > > > >>>> timeout to something larger than the default 60s? Put another
> way,
> > > > what
> > > > >>>> resources (and how much of them) does a scanner take up on a
> > thrift
> > > > >> server
> > > > >>>> or region server?
> > > > >>>>
> > > > >>>> Also, to confirm -- I believe "hbase.rpc.timeout" is the setting
> > in
> > > > >>>> question here, but someone please correct me if I'm wrong.
> > > > >>>>
> > > > >>>> Thanks,
> > > > >>>> - Dan
> > > > >>>>
> > > > >>>>
> > > > >>>>
> > > > >>
> > > > >>
> > > >
> > > >
> > >
> >
>
