In-Memory Performance

Matt Savona matt.savona at gmail.com
Tue Aug 2 20:11:07 EDT 2011


Hi Eric,

I this test, R=1 (the default).

Thanks!

- Matt

On Tue, Aug 2, 2011 at 4:35 PM, Eric Moritz <eric at themoritzfamily.com> wrote:
> When you were doing the reads, did you set the r-value to 1?  This
> will speed up reads in a read heavy app because only one node has to
> be in agreement about the object.
>
> Eric.
>
> On Tue, Aug 2, 2011 at 11:22 AM, Matt Savona <matt.savona at gmail.com> wrote:
>> Hi all,
>>
>> My colleagues and I are evaluating Riak as a persistent, replicated K-V store.
>>
>> I have a fairly simple (and not so scientific) test that reads and
>> writes 5000 objects that are 32K in size. I am particularly interested
>> in squeezing every last bit of performance out of Riak in a very
>> read-heavy environment. I want to avoid hitting disk for reads as much
>> as possible; our entire content set is much larger than could ever be
>> stored in RAM, but preferably hot/active objects will remain resident
>> in memory until various conditions may force them to be evicted. While
>> the content set is quite large, the number of active keys represent a
>> very small portion of the data which could easily fit in RAM.
>>
>> I've been running the same test against Riak given various
>> combinations of backends and access protocols (HTTP vs. PB).
>>
>> My numbers can be seen in this screenshot:
>> http://img824.imageshack.us/img824/3185/riakperformance.png
>>
>> It is quite evident (and perhaps obvious) that Protocol Buffer
>> performance is noticeably better than HTTP in most cases.
>>
>> What is confusing to me is the performance of purely in-memory
>> backends. Notably, GB Trees and LRU Cache (and even Innostore), at
>> best took 14s to retrieve 5000 32K objects. The exact same test
>> against Membase took just 6s.
>>
>> Perhaps I'm not comparing apples to apples (Riak in-memory versus
>> Membase). Do my tests look reasonable and do the numbers look roughly
>> in-line with expectations? Is there any way to squeeze more juice out
>> of Riak? A purely in-memory/non-persistent backend will not suffice
>> for our ultimate needs, but for testing purposes I'm just trying to
>> see if I can get read performance more in line with what we're seeing
>> with Membase. We love everything about it, but we haven't yet hit the
>> performance we were hoping for.
>>
>> Thanks in advance!
>>
>> - Matt
>>
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>




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