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Date: Thu, 27 Oct 2011 03:32:13 +0400
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Subject: Re: High latency (40ms) and low request rate (10 rps) under windows
From: Konstantin Cherkasoff <k.cherkasoff@gmail.com>
To: dev@couchdb.apache.org
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Hi!

> What happens when you set delayed_commits to true?
With delayed_commits I got about 150 rps so delayed_commits mode is 15
times faster.

> With that off you are requiring an fsync (iirc) =C2=A0after every value w=
ritten and then are at the
> mercy at your disks write performance (but not in the sense of burst-writ=
e
> as these are individual, disparate write requests coming in).

Yes, I understand that many small writes and fsyncs can be a
bottleneck in this case.
But I found that the increase of number of concurrent requests lead to
an increase in the request rate.
For example (100 concurent requests)
> ab -k -t 10 -c 100 -n 1000000 -p ab.json -T "application/json" http://loc=
alhost:5984/bench
shows about 300 RPS (writes and fsyncs) on the same hardware.

So, I suppose that 10 requests per second actually is not the limit
for this hard disk.
And there may be some other problem.

> Also, is this build Couch Single Server from Couchbase or some other Wind=
ows build of Couch?
I tried Couchbase 1.2.0 and
this build https://github.com/downloads/dch/couchdb/setup-couchdb-1.1.0+COU=
CHDB-1152_otp_R14B03.exe


--
Konstantin