High CPU on a single node in production

Luke Bakken lbakken at basho.com
Wed Jan 6 09:39:55 EST 2016

Hi Josh,

1024 is too large of a ring size for 10 nodes. If it's possible to
rebuild your cluster using a ring size of 128 or 256 that would be
ideal (http://docs.basho.com/riak/latest/ops/building/planning/cluster/#Ring-Size-Number-of-Partitions).
Ring resizing is possible as well

Have all of our recommended performance tunings been applied to every
node in this cluster?
(http://docs.basho.com/riak/latest/ops/tuning/linux/) - these can have
a dramatic effect on cluster performance.

Luke Bakken
lbakken at basho.com

On Tue, Jan 5, 2016 at 10:52 AM, Josh Yudaken <josh at smyte.com> wrote:
> Hi,
> We're attempting to use Riak as our primary key-value and search
> database for an analytics-typed solution to blocking spam/fraud.
> As we expect to eventually be handling a huge amount of data, I
> started with a ring size of 1024. We currently have 10 nodes on Google
> Cloud n1-standard-16 instances [ 16 cores, 60gb RAM, 720gb local ssd.
> ]. Disks are at about 60% usage [ roughly 175gb leveldb, 16gb yz, 45gb
> anti_entropy, 6gb yz_anti_entropy ], and request wise we're at about
> 20k/min get, 4k/min set. Load average is usually around 6.
> I'm assuming most of the issues we're seeing are Yokozuna related, but
> we're seeing a ton of tcp timeouts during handoffs, very slow get/set
> queries, and a slew of other errors.
> Right now I'm trying to debug an issue where one of the 10 nodes
> pegged all the cpu cores. Mostly with the `bean` process.
> # riak-admin top
> Output server crashed: connection_lost
> With few other options (as it was causing slow queries across the
> cluster) I stopped the server and saw hundreds of the following
> (interesting) messages in the log::
> 2016-01-05 18:28:28.573 [info]
> <0.4958.0>@yz_index_hashtree:close_trees:557 Deliberately marking YZ
> hashtree {1458647141945490998441568260777384029383167049728,3} for
> full rebuild on next restart
> As well as a ton of (I think related?):
> 2016-01-05 18:28:31.153 [error] <0.5982.0>@yz_kv:index_internal:237
> failed to index object
> {{<<"features">>,<<"features">>},<<"0NKqMtj3O6_">>} with error
> {noproc,{gen_server,call,[yz_entropy_mgr,{get_tree,1120389438774178506630754486017853682060456099840},infinity]}}
> because [{gen_server,call,3,[{file,"gen_server.erl"},{line,188}]},{yz_kv,get_and_set_tree,1,[{file,"src/yz_kv.erl"},{line,452}]},{yz_kv,update_hashtree,4,[{file,"src/yz_kv.erl"},{line,340}]},{yz_kv,index,7,[{file,"src/yz_kv.erl"},{line,295}]},{yz_kv,index_internal,5,[{file,"src/yz_kv.erl"},{line,224}]},{riak_kv_vnode,actual_put,6,[{file,"src/riak_kv_vnode.erl"},{line,1619}]},{riak_kv_vnode,perform_put,3,[{file,"src/riak_kv_vnode.erl"},{line,1607}]},{riak_kv_vnode,do_put,7,[{file,"src/riak_kv_vnode.erl"},{line,1398}]}]
> For reference the TCP timeout error looks like:
> 2016-01-01 01:09:50.522 [error]
> <0.8430.6>@riak_core_handoff_sender:start_fold:272 hinted transfer of
> riak_kv_vnode from 'riak at riak25-2.c.authbox-api.internal'
> 185542200051774784537577176028434367729757061120 to
> 'riak at riak27-2.c.authbox-api.internal'
> 185542200051774784537577176028434367729757061120 failed because of TCP
> recv timeout
> Any suggestions about where to look?
> Regards,
> Josh

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