Hi Dean There is a patch attached in https://issues.apache.org/jira/browse/HBASE-6048 by Chunhui. Hope it addresses your problem. Can you take a look at it and see if it is working fine?
Regards Ram On Fri, Jan 24, 2014 at 10:16 AM, ramkrishna vasudevan < [email protected]> wrote: > Hi Dean > > I mentioned those JIRAs to highlight the fact that the bug was open and it > was not fixed. I think better we fix this in 0.94 also, so that users > using this feature do not run into surprises. And we are sorry that the > feature that worked well for you in 0.92, did not work out in 0.94. It > should be resolved IMO. > > You are going for a patch from your side? If so, that would be great. > > Regards > Ram > > > On Thu, Jan 23, 2014 at 11:31 PM, Dean <[email protected]> wrote: > >> Hi Ramkrishna, >> >> I had taken the experimental label to mean "use at your own risk" when >> the feature was released in 0.92. After some judicious testing in the >> spirit of "use at your own risk", we found the feature worked well for our >> use case. In 0.94, we had expected off-heap cache to be the same as 0.92, >> or perhaps even with a few small improvements. It came as a bit of a >> surprise that the feature went from experimental to plain broken. >> >> Perhaps my interpretation of "experimental" was off base to begin with - >> in retrospect it may have been presumptuous to assume that an >> "experimental" feature would only become more mature and eventually >> graduate to a full-fledged feature. I can see how such a feature might go >> the other way, quietly going from experimental to deprecated to broken. >> >> We'd love a viable off-heap cache solution - we're currently scrambling a >> bit for options in production since we're not able to roll back to 0.92.1. >> The HBASE-7404 solution that Ted pointed out looks awesome, but we're not >> in a position to move to 0.96 to take advantage of it. At this point, I'm >> fishing for options. We run a mix of random reads and scans. We disable >> block cache for scans to improve random read performance. With a chunk of >> RAM allocated to off-heap cache, this seemed to work well. Now that we're >> dominated by filesystem cache, scans with block cache disabled still trash >> the cache, significantly hurting our random read performance. We've got >> short-circuit reads and Hbase checksums enabled in an attempt to gain back >> some of the lost perf, but they are more of a band-aid than a fix for root >> cause. Any suggestions are much appreciated. >> >> Cheers, >> >> Dean >> > >
