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From Oleg Kalnichevski <ol...@apache.org>
Subject Re: Thread Contention (due to use of proxys) in HttpClient 4.3
Date Mon, 12 May 2014 12:50:42 GMT
On Mon, 2014-05-12 at 13:21 +0100, Daniel Feist wrote:
> >> 2) Can I expect 4.2 to scale better?
> >
> > I do not think so. In my tests HC 4.3 performs better than 4.2. There
> > have also been reports
> Even with high concurrency of say 200 and high TPS, for example in a
> http proxy scenario?

Yes, also with over 200 concurrent connections. However, for HTTP proxy
scenarios one may be advised to consider using a non-blocking model.

> >> 3) Is there a way of configuring 4.3.3 to not use proxys?
> >
> > No, there is not. The cost of dynamic proxies in modern JREs is believed
> > to be low.
> The problem I see isn't the use of proxies, it is in the creation of
> these proxy instances which is synchnorized on a HashMap 'cache' in
> two places in java.lang.reflect.Proxy.getProxyClass0(ClassLoader,
> Class<?>...).  This is visible in the profiler screenshot I shared
> too.
> This probably isn't an issue with low concurrency, or high concurrency
> and low TPS, but in my testing/profiling it comes up as an issue.

I use this micro-benchmark to benchmark HttpClient performance between
versions as well compared to other implementations.


I am open to the idea of replacing dynamic proxies with hand crafted
classes, but I would like to see more evidence that
java.lang.reflect.Proxy is indeed a bottleneck.


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