Yes Mohit, that's the cause! HBase is read values not present in datatable, which leads to very fast read performance. When I change it to reading valid values in data table, it is back to normal (read slower than write). Thank you a lot for the discussion. Yun
On Sat, Nov 3, 2012 at 11:11 AM, Mohit Anchlia <mohitanch...@gmail.com>wrote: > Some of the things to look at is I/O on the disk, CPU on the server. Look > at CPU and java thread dumps on the client. I use Ganglia to look at server > stats and it is often very helpful. > > In my opinon best thing would be to add some code around various HBase > calls to see where time is being spent on the client side and then go from > there. > > Do your reads read same data set as writes? > > On Sat, Nov 3, 2012 at 7:09 AM, yun peng <pengyunm...@gmail.com> wrote: > > > Hi, the throughput for write-only workload is 450 ops/sec and for > read-only > > 900 ops/sec. I am using the same machine (1-core CPU, 2G mem) for client > to > > drive workload into hbase/hdfs... one thread is used in client side. For > > this workload, it looks client should not be the bottleneck... Btw, is > > there anyway to verify this. > > Thanks, > > Yun > > > > On Sat, Nov 3, 2012 at 1:04 AM, Mohit Anchlia <mohitanch...@gmail.com > > >wrote: > > > > > What load do you see on the system? I am wondering if bottleneck is on > > the > > > client side. > > > > > > On Fri, Nov 2, 2012 at 9:07 PM, yun peng <pengyunm...@gmail.com> > wrote: > > > > > > > Hi, All, > > > > In my HBase cluster, I observed Put() executes faster than a Get(). > > Since > > > > HBase is optimized towards write, I wonder what may affect Put > > > performance > > > > in a distributed setting below. > > > > > > > > Hbase setup: > > > > My HBase cluster are of three nodes, in which one hosts zookeeper and > > > > HMaster, and two slaves. HBase cluster is attached to HDFS which > > resides > > > on > > > > a separated cluster. The machines are fairly commodity or lower end, > > with > > > > 2G memory and 1-core CPU. > > > > > > > > Observed results: > > > > I test the Put and Get latency on this setup, and find out Put runs > > > slower > > > > than Get (which is a bit surprising to me.) In case anyone is > > interested, > > > > in my result, Put() takes around 3000us and Get only in 1000us (so I > > > think > > > > it does not touch disk). > > > > > > > > What could possibly slow dow Put() and speed up Get() performance in > > > HBase? > > > > Does this possibly have to do with distributed setting, like Put > needs > > > > update multiple (duplicated) copies while Gets only one.. I am quite > > > > newbie to HBase internal and not familiar with HBase Put/Get code > path, > > > has > > > > anyone here have similar experiences? > > > > > > > > Thanks, > > > > Yun > > > > > > > > > >
