Smaller block size (32K) does not give any performance gain and this is strange, to say the least.
On Wed, Jul 31, 2013 at 9:33 PM, lars hofhansl <[email protected]> wrote: > Would be interesting to profile MultiGet. With RTT of 0.1ms, the internal > RS friction is probably the main contributor. > In fact MultiGet just loops over the set at the RS and calls single gets > on the various regions. > > Each Get needs to reseek into the block (even when it is cached, since KVs > have variable size). > > There are HBASE-6136 and HBASE-8362. > > > -- Lars > > ________________________________ > From: Vladimir Rodionov <[email protected]> > To: [email protected]; lars hofhansl <[email protected]> > Sent: Wednesday, July 31, 2013 7:27 PM > Subject: Re: HBase read perfomnance and HBase client > > > Some final numbers : > > Test config: > > HBase 0.94.6 > blockcache=true, block size = 64K, KV size = 62 bytes (raw). > > 5 Clients: 96GB, 16(32) CPUs (2.2Ghz), CentOS 5.7 > 1 RS Server: the same config. > > Local network with ping between hosts: 0.1 ms > > > 1. HBase client hits the wall at ~ 50K per sec regardless of # of CPU, > threads, IO pool size and other settings. > 2. HBase server was able to sustain 170K per sec (with 64K block size). All > from block cache. KV size = 62 bytes (very small). This is for single Get > op, 60 threads per client, 5 clients (on different hosts) > 3. Multi - get hits the wall at the same 170K-200K per sec. Batch size > tested: 30, 100. The same performance absolutely as with batch size = 1. > Multi get has some internal issues on RegionServer side. May be excessive > locking or some thing else. > > > > > > On Tue, Jul 30, 2013 at 2:01 PM, Vladimir Rodionov > <[email protected]>wrote: > > > 1. SCR are enabled > > 2. Single Configuration for all table did not work well, but I will try > it > > again > > 3. With Nagel I had 0.8ms avg, w/o - 0.4ms - I see the difference > > > > > > On Tue, Jul 30, 2013 at 1:50 PM, lars hofhansl <[email protected]> wrote: > > > >> With Nagle's you'd see something around 40ms. You are not saying 0.8ms > >> RTT is bad, right? Are you seeing ~40ms latencies? > >> > >> This thread has gotten confusing. > >> > >> I would try these: > >> * one Configuration for all tables. Or even use a single > >> HConnection/Threadpool and use the HTable(byte[], HConnection, > >> ExecutorService) constructor > >> * disable Nagle's: set both ipc.server.tcpnodelay and > >> hbase.ipc.client.tcpnodelay to true in hbase-site.xml (both client *and* > >> server) > >> * increase hbase.client.ipc.pool.size in client's hbase-site.xml > >> * enable short circuit reads (details depend on exact version of > Hadoop). > >> Google will help :) > >> > >> -- Lars > >> > >> > >> ----- Original Message ----- > >> From: Vladimir Rodionov <[email protected]> > >> To: [email protected] > >> Cc: > >> Sent: Tuesday, July 30, 2013 1:30 PM > >> Subject: Re: HBase read perfomnance and HBase client > >> > >> This hbase.ipc.client.tcpnodelay (default - false) explains poor single > >> thread performance and high latency ( 0.8ms in local network)? > >> > >> > >> On Tue, Jul 30, 2013 at 1:22 PM, Vladimir Rodionov > >> <[email protected]>wrote: > >> > >> > One more observation: One Configuration instance per HTable gives 50% > >> > boost as compared to single Configuration object for all HTable's - > from > >> > 20K to 30K > >> > > >> > > >> > On Tue, Jul 30, 2013 at 1:17 PM, Vladimir Rodionov < > >> [email protected] > >> > > wrote: > >> > > >> >> This thread dump has been taken when client was sending 60 requests > in > >> >> parallel (at least, in theory). There are 50 server handler threads. > >> >> > >> >> > >> >> On Tue, Jul 30, 2013 at 1:15 PM, Vladimir Rodionov < > >> >> [email protected]> wrote: > >> >> > >> >>> Sure, here it is: > >> >>> > >> >>> http://pastebin.com/8TjyrKRT > >> >>> > >> >>> epoll is not only to read/write HDFS but to connect/listen to > clients > >> as > >> >>> well? > >> >>> > >> >>> > >> >>> On Tue, Jul 30, 2013 at 12:31 PM, Jean-Daniel Cryans < > >> >>> [email protected]> wrote: > >> >>> > >> >>>> Can you show us what the thread dump looks like when the threads > are > >> >>>> BLOCKED? There aren't that many locks on the read path when reading > >> >>>> out of the block cache, and epoll would only happen if you need to > >> hit > >> >>>> HDFS, which you're saying is not happening. > >> >>>> > >> >>>> J-D > >> >>>> > >> >>>> On Tue, Jul 30, 2013 at 12:16 PM, Vladimir Rodionov > >> >>>> <[email protected]> wrote: > >> >>>> > I am hitting data in a block cache, of course. The data set is > very > >> >>>> small > >> >>>> > to fit comfortably into block cache and all request are directed > to > >> >>>> the > >> >>>> > same Region to guarantee single RS testing. > >> >>>> > > >> >>>> > To Ted: > >> >>>> > > >> >>>> > Yes, its CDH 4.3 . What the difference between 94.10 and 94.6 > with > >> >>>> respect > >> >>>> > to read performance? > >> >>>> > > >> >>>> > > >> >>>> > On Tue, Jul 30, 2013 at 12:06 PM, Jean-Daniel Cryans < > >> >>>> [email protected]>wrote: > >> >>>> > > >> >>>> >> That's a tough one. > >> >>>> >> > >> >>>> >> One thing that comes to mind is socket reuse. It used to come up > >> more > >> >>>> >> more often but this is an issue that people hit when doing loads > >> of > >> >>>> >> random reads. Try enabling tcp_tw_recycle but I'm not > guaranteeing > >> >>>> >> anything :) > >> >>>> >> > >> >>>> >> Also if you _just_ want to saturate something, be it CPU or > >> network, > >> >>>> >> wouldn't it be better to hit data only in the block cache? This > >> way > >> >>>> it > >> >>>> >> has the lowest overhead? > >> >>>> >> > >> >>>> >> Last thing I wanted to mention is that yes, the client doesn't > >> scale > >> >>>> >> very well. I would suggest you give the asynchbase client a run. > >> >>>> >> > >> >>>> >> J-D > >> >>>> >> > >> >>>> >> On Tue, Jul 30, 2013 at 11:23 AM, Vladimir Rodionov > >> >>>> >> <[email protected]> wrote: > >> >>>> >> > I have been doing quite extensive testing of different read > >> >>>> scenarios: > >> >>>> >> > > >> >>>> >> > 1. blockcache disabled/enabled > >> >>>> >> > 2. data is local/remote (no good hdfs locality) > >> >>>> >> > > >> >>>> >> > and it turned out that that I can not saturate 1 RS using one > >> >>>> >> (comparable in CPU power and RAM) client host: > >> >>>> >> > > >> >>>> >> > I am running client app with 60 read threads active (with > >> >>>> multi-get) > >> >>>> >> that is going to one particular RS and > >> >>>> >> > this RS's load is 100 -150% (out of 3200% available) - it > means > >> >>>> that > >> >>>> >> load is ~5% > >> >>>> >> > > >> >>>> >> > All threads in RS are either in BLOCKED (wait) or in IN_NATIVE > >> >>>> states > >> >>>> >> (epoll) > >> >>>> >> > > >> >>>> >> > I attribute this to the HBase client implementation which > seems > >> >>>> to be > >> >>>> >> not scalable (I am going dig into client later on today). > >> >>>> >> > > >> >>>> >> > Some numbers: The maximum what I could get from Single get (60 > >> >>>> threads): > >> >>>> >> 30K per sec. Multiget gives ~ 75K (60 threads) > >> >>>> >> > > >> >>>> >> > What are my options? I want to measure the limits and I do not > >> >>>> want to > >> >>>> >> run Cluster of clients against just ONE Region Server? > >> >>>> >> > > >> >>>> >> > RS config: 96GB RAM, 16(32) CPU > >> >>>> >> > Client : 48GB RAM 8 (16) CPU > >> >>>> >> > > >> >>>> >> > Best regards, > >> >>>> >> > Vladimir Rodionov > >> >>>> >> > Principal Platform Engineer > >> >>>> >> > Carrier IQ, www.carrieriq.com > >> >>>> >> > e-mail: [email protected] > >> >>>> >> > > >> >>>> >> > > >> >>>> >> > Confidentiality Notice: The information contained in this > >> message, > >> >>>> >> including any attachments hereto, may be confidential and is > >> >>>> intended to be > >> >>>> >> read only by the individual or entity to whom this message is > >> >>>> addressed. If > >> >>>> >> the reader of this message is not the intended recipient or an > >> agent > >> >>>> or > >> >>>> >> designee of the intended recipient, please note that any review, > >> use, > >> >>>> >> disclosure or distribution of this message or its attachments, > in > >> >>>> any form, > >> >>>> >> is strictly prohibited. If you have received this message in > >> error, > >> >>>> please > >> >>>> >> immediately notify the sender and/or > [email protected] > >> >>>> >> delete or destroy any copy of this message and its attachments. > >> >>>> >> > >> >>>> > >> >>> > >> >>> > >> >> > >> > > >> > >> > > >
