Beginners performance problem

Lars J. Nilsson lars.j.nilsson at
Fri Feb 22 10:21:14 EST 2013

Hi all,

I'm micro-testing a simple update pattern (key + short json document) on my
local workstation (8 core intel CPU, 8 gig of RAM, 10K disk) to get
baseline before moving to cluster on AWS. With Riak I get about 60 mods/s
before maxing out (as compared to approx 3000 mods/s on a
vanilla MySQL using exactly the same code).

It feels like I must be doing something hideously wrong. (For the record,
I'm a decent Java programmer but a riak/erlang n00b).

Riak is installed via a vanilla Ununtu 12.04 package as described in the
docs. The test ran on the same disk as the mentioned MySQL test. The same
Java code was doing both tests (just a DAO swapped).

The bucket was using n_val = 1.

The problem seems to be in high disk-writing, despite the low load. Here's
what iostat says during the run:

wrqm/s : 434.50
w/s: 182.90
wkB/s: 2618.00
avgrq-sz: 28.63
%util: 10.60

Which seems to be too much considering the small load (the stored JSON
blobs are roughly 1K each).

I'm using the official PB Java client.

This is an evaluation for a customer. Any hint of what I'm missing or what
the problem could be would be appreciated.

/Lars J. Nilsson
Executive VP, Cubeia Ltd
+46 (0) 704 / 10 69 53
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