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From Andrew Purtell <apurt...@apache.org>
Subject Re: deprecating (old) metrics in favor of metrics2 framework
Date Wed, 11 Jul 2012 18:57:09 GMT
On Wed, Jul 11, 2012 at 10:50 AM, Elliott Clark <eclark@stumbleupon.com> wrote:
[...]
>
> The reflection option seems like it would be a big perf hit.  Reflection
> basically means that nothing ever gets inlined so all function calls into
> metrics2 code would be very expensive.  Since it seems like we are adding
> more and more instrumentation this perf impact would only grow.
>  In addition as more hadoop versions come out all of our reflection code
> would get much more complicated and brittle.
>
> The conditionally loaded jar would be nice in that the JIT would only see
> one version of the factory classes on the classpath and everything could be
> optimized just like any other jvm run jit'd code. In addition there are
> other places that we use reflection to do things conditionally and a
> conditionally loaded jar would be nice.

Coprocessors are a solution close to conditionally loaded JARs: there
is not reflection, very frequently executed code would be JITed, the
only thing missing is direct inlining.

More and more (useful) metrics are going into hot paths, we want all
three I think.

We keep inching toward DI.

Best regards,

   - Andy

Problems worthy of attack prove their worth by hitting back. - Piet
Hein (via Tom White)

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