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From Konstantin Cherkasov <c...@imarto.net>
Subject Re: High latency (40ms) and low request rate (10 rps) under windows
Date Tue, 25 Oct 2011 21:19:00 GMT
Hi!

> 1. delayed_commits helps you in high concurrency (batch mode) and less 
> in no concurrency.
You are wrong.

curl -X PUT -H "Content-Type: application/json" http://127.0.0.1:5984/_config/couchdb/delayed_commits
-d "\"true\""
ab -k -c 1 -n 1000 -p ab.json -T "application/json" http://localhost:5984/bench

Requests per second:    173.71 [#/sec] (mean)

curl -X PUT -H "Content-Type: application/json" http://127.0.0.1:5984/_config/couchdb/delayed_commits
-d "\"false\""
ab -k -c 1 -n 1000 -p ab.json -T "application/json" http://localhost:5984/bench

Requests per second:    10.15 [#/sec] (mean)

CPU & HDD utilization 0.01%.
It looks like there are some delays in TCP or HTTP.


> 2. If one wants to send in the same session lots of documents, that 
> someone uses bulk operation. Otherwise, high concurrency comes in play 
> by the means of batch mode.

Well, in real life there are many cases when events or data come not in batches but one by
one.

In truth, it seems to me that this BATCH MODE MANTRA leads to defects in the code that simply
are not investigated.

"OMG! My database do 10 requests per second (for ex. Postgres do 1000 rps on the same hardware
with fsync on)
"Forget this, just use BATCH MODE"



-- 
 Konstantin Cherkasov


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