Use klauspost/compress/gzip instead of standard library

[agnivade]

This gives 40-50% improvements in CPU with very minor increase
in memory, just as a drop-in replacement. I think that is a very reasonable tradeoff.

The library is mature and safe to be used in production.

name                 old time/op    new time/op    delta
GzipHandler_S2k-8      74.9µs ± 2%    34.4µs ± 2%  -54.07%  (p=0.000 n=10+9)
GzipHandler_S20k-8      379µs ± 1%     226µs ± 3%  -40.42%  (p=0.000 n=9+10)
GzipHandler_S100k-8    1.95ms ± 2%    1.15ms ± 1%  -41.27%  (p=0.000 n=9+9)
GzipHandler_P2k-8      24.3µs ±25%    10.7µs ±25%  -55.80%  (p=0.000 n=10+10)
GzipHandler_P20k-8      132µs ± 2%      75µs ± 1%  -42.95%  (p=0.000 n=9+10)
GzipHandler_P100k-8     658µs ± 2%     371µs ± 3%  -43.68%  (p=0.000 n=9+10)

name                 old alloc/op   new alloc/op   delta
GzipHandler_S2k-8      7.71kB ± 5%    9.13kB ± 7%  +18.33%  (p=0.000 n=10+10)
GzipHandler_S20k-8     65.1kB ± 3%    70.3kB ± 3%   +8.05%  (p=0.000 n=10+10)
GzipHandler_S100k-8     348kB ± 4%     382kB ± 2%   +9.85%  (p=0.000 n=10+10)
GzipHandler_P2k-8      7.60kB ± 1%    7.93kB ± 2%   +4.33%  (p=0.000 n=10+10)
GzipHandler_P20k-8     64.4kB ± 1%    66.3kB ± 2%   +2.92%  (p=0.000 n=10+10)
GzipHandler_P100k-8     304kB ± 1%     309kB ± 1%   +1.67%  (p=0.000 n=10+9)

name                 old allocs/op  new allocs/op  delta
GzipHandler_S2k-8        21.0 ± 0%      21.0 ± 0%     ~     (all equal)
GzipHandler_S20k-8       24.0 ± 0%      24.0 ± 0%     ~     (all equal)
GzipHandler_S100k-8      27.0 ± 0%      27.0 ± 0%     ~     (all equal)
GzipHandler_P2k-8        21.0 ± 0%      21.0 ± 0%     ~     (all equal)
GzipHandler_P20k-8       24.0 ± 0%      24.0 ± 0%     ~     (all equal)
GzipHandler_P100k-8      26.0 ± 0%      26.0 ± 0%     ~     (all equal)

I do see a PR open for swappable gzip implementations, but that is open for several months. I don't mind if that goes in as long as I can replace the standard library implementation.

It is my hope that this will be upstreamed. Otherwise we would just have to fork this ourselves. Gzipping is a very intensive operation in our workload and this is a great cheap way to get some gains.

[dolmen]

There are already multiple replacements of the gzip implementation proposed.

What we need is #106 so that anyone can choose the gzip implementation he/she likes.

[agnivade]

That would work too.