W ----- Original Message ----- From: Dmitriy Lyubimov [mailto:dlie...@gmail.com] Sent: Friday, April 22, 2011 02:50 AM To: user@hbase.apache.org <user@hbase.apache.org> Subject: Re: 0.90 latency performance, cdh3b4
> > You saw "HBASE-2939 Allow Client-Side Connection Pooling"? Would that help? Ok just read thru the issue. That's exactly what i thought upon reading the code in HBaseClient class. Although in my cluster it did not seem to have more than about 20% effect and it was more or less evaporated after 3 connections. (1 to 3 has noticeable jump but there was no much difference between 3 and 10. But then again i suspect my problem is network but not the threading -- although with a mix of longer and shorter messages it may become an apparent nuisance indeed). > > >> And tcp doesn't seem to perform very >> well for some reason in this scenario. >> > > What do you see here D? > > >> The next thing i did was to enable tcp_nodelay on both client and >> server. That got us down even more to 13ms average. >> > > Thats a big difference. > > >> However, it is still about two times slower if i run all processes at >> the same machine (i get around 6-7ms average TTLBs for the same type >> of scan). >> >> Ping time for about same packet size between hosts involved seems to >> revolve around 1ms. Where another 5ms average time are getting lost is >> still a mystery. But oh well i guess it is as good as it gets. >> In real life hbase applications traffic would be much more uniformly >> distributed among regions and this would be much less of an issue >> perhaps. >> >> I also suspect that using udp for short scans and gets might reduce >> latency a bit as well. >> > > Thank you Dmitriy for digging in. Good stuff. > St.Ack > This communication is intended only for the addressee(s), may contain confidential information, and may be protected by US and other laws. We do not waive any confidentiality by misdelivery. If you receive this communication in error, any use, dissemination, printing or copying is strictly prohibited; please destroy all electronic and paper copies and notify the sender immediately. Nothing in this email is intended to constitute (1) investment or trading advice or recommendations or any advertisement or (2) a solicitation of an investment in any jurisdiction in which such a solicitation would be unlawful.
