@pradeep scanner caching should not be an issue since data transferred to the client is tiny.
@lars Yes, the data might be small for this particular case :-) I have checked everything I can think of on RS (CPU, network, Hbase console, uptime etc) and nothing stands out, except for the pings (network pings). There are 5 regions on 7, 18, 19, and 23 the others have 4. hdfsBlocksLocalityIndex=100 on all RS (was that the correct metric?) -Kristoffer On Sat, Dec 21, 2013 at 9:44 PM, lars hofhansl <[email protected]> wrote: > Hi Kristoffer, > For this particular problem. Are many regions on the same RegionServers? > Did you profile those RegionServers? Anything weird on that box? > Pings slower might well be an issue. How's the data locality? (You can > check on a RegionServer's overview page). > If needed, you can issue a major compaction to reestablish local data on > all RegionServers. > > > 32 cores matched with only 4G of RAM is a bit weird, but with your tiny > dataset it doesn't matter anyway. > > 10m rows across 96 regions is just about 100k rows per region. You won't > see many of the nice properties for HBase. > Try with 100m (or better 1bn rows). Then we're talking. For anything below > this you wouldn't want to use HBase anyway. > (100k rows I could scan on my phone with a Perl script in less than 1s) > > > With "ping" you mean an actual network ping, or some operation on top of > HBase? > > > -- Lars > > > > ________________________________ > From: Kristoffer Sjögren <[email protected]> > To: [email protected] > Sent: Saturday, December 21, 2013 11:17 AM > Subject: Performance tuning > > > Hi > > I have been performance tuning HBase 0.94.6 running Phoenix 2.2.0 the last > couple of days and need some help. > > Background. > > - 23 machine cluster, 32 cores, 4GB heap per RS. > - Table t_24 have 24 online regions (24 salt buckets). > - Table t_96 have 96 online regions (96 salt buckets). > - 10.5 million rows per table. > - Count query - select (*) from ... > - Group by query - select A, B, C sum(D) from ... where (A = 1 and T >= 0 > and T <= 2147482800) group by A, B, C; > > What I found ultimately is that region servers 19, 20, 21, 22 and 23 > are consistently > 2-3x slower than the others. This hurts overall latency pretty bad since > queries are executed in parallel on the RS and then aggregated at the > client (through Phoenix). In Hannibal regions spread out evenly over region > servers, according to salt buckets (phoenix feature, pre-create regions and > a rowkey prefix). > > As far as I can tell, there is no network or hardware configuration > divergence between the machines. No CPU, network or other notable > divergence > in Ganglia. No RS metric differences in HBase master console. > > The only thing that may be of interest is that pings (within the cluster) > to > bad RS is about 2-3x slower, around 0.050ms vs 0.130ms. Not sure if > this is significant, > but I get a bad feeling about it since it match exactly with the RS that > stood out in my performance tests. > > Any ideas of how I might find the source of this problem? > > Cheers, > -Kristoffer >
