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From Konstantin Cherkasoff <k.cherkas...@gmail.com>
Subject Re: High latency (40ms) and low request rate (10 rps) under windows
Date Wed, 26 Oct 2011 23:32:13 GMT
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)  after every value written and then
are at the
> mercy at your disks write performance (but not in the sense of burst-write
> 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://localhost: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 Windows build of
Couch?
I tried Couchbase 1.2.0 and
this build https://github.com/downloads/dch/couchdb/setup-couchdb-1.1.0+COUCHDB-1152_otp_R14B03.exe


--
Konstantin

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