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From Jared Jacobs <ja...@kaching.com>
Subject Re: Poor performance of pooled connections worse in 4.0
Date Thu, 05 Nov 2009 23:24:02 GMT
> What is the point of having 10 connection limit and using 50 worker
> threads?

To simulate heavy load (more demand than supply). It's irrelevant. Make the
numbers the same and you'll still see the latency problem.

> Regardless of what the max connections per host limit is set to, though, at
>> least the first request should not block at all.
> Why?

Because the pool is empty the first time around. To be clear, I meant block
*waiting for a connection from the pool to become available*.

All these numbers are meaningless given such a small number of requests.
>>  You should be executing 10,000 HTTP requests in order to get any meaningful
>> performance data.
In our production environment, we're talking to reliable services with
strict SLAs over fast, reliable connections. We do tens of thousands of
requests, and as I mentioned in my first email, we saw a large increase in
request times when we upgraded from httpclient 3.1 to 4.0.

Some things become clearer when you isolate factors. Hence my benchmarks.
Any statistician will tell you that when the minimum of 50 samples increases
by 10x, it is statistically significant. The samples are coming from two
very different populations.

Oleg, I've sent you my benchmark source code off-list. Feel free to use it,
or not. I would be interested in any performance measurements that you or
someone else at Apache has done.

Best regards,

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