Scans on RS 19 and 23, which have 5 regions instead of 4, stands out more than scans on RS 20, 21, 22. But scans on RS 7 and 18, that also have 5 regions are doing fine, not best, but still in the mid-range.
On Sat, Dec 21, 2013 at 11:51 PM, Kristoffer Sjögren <[email protected]>wrote: > Yeah, im doing a count(*) query on the 96 region table. Do you mean to > check network traffic between RS? > > From debugging phoenix code I can see that there are 96 scans sent and > each response returned back to the client contain only the sum of rows, > which are then aggregated and returned. So the traffic between client and > each RS is very small. > > > > > On Sat, Dec 21, 2013 at 11:35 PM, lars hofhansl <[email protected]> wrote: > >> Thanks Kristoffer, >> >> yeah, that's the right metric. I would put my bet on the slower network. >> But you're also doing a select count(*) query in Phoenix, right? So >> nothing should really be sent across the network. >> >> When you do the queries, can you check whether there is any network >> traffic? >> >> -- Lars >> >> >> >> ________________________________ >> From: Kristoffer Sjögren <[email protected]> >> To: [email protected]; lars hofhansl <[email protected]> >> Sent: Saturday, December 21, 2013 1:28 PM >> Subject: Re: Performance tuning >> >> >> @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 >> > >> > >
