Pkg 1.5.2: clone git registries by default on Windows

[StefanKarpinski]

See https://discourse.julialang.org/t/status-of-pkg-speed-improvements-outside-us-in-v1-5/46395/17. In 1.5.2, we should clone registries by default on Windows since unpacking tarballs with lots of small files is so slow there.

[DilumAluthge]

Sounds like a good plan.

I'm assuming we'll do this not only for the 1.5.2 release, but also for master, right?

[DilumAluthge]

Or are you hoping to have "use the registry without unpacking the tarball" functionality ready in time for 1.6?

[StefanKarpinski]

We should do it on master for now but for 1.6 I am hoping to implement reading the registry directly from the tarball. Once I've hooked up using Tar.jl for extracting tarballs, this shouldn't be very hard.

[niclasmattsson]

FYI, Microsoft is making progress with tarball unpacking: microsoft/Windows-Dev-Performance#27.

[KristofferC]

Thanks, that's a very interesting link.

[fredrikekre]

Would be nice to see how Julia/Pkg behaves after that update. Is there a way to know if you have it?

[niclasmattsson]

I'm sure you can just look it up in the Windows Update log somehow, but I brute-forced it. I downloaded the firefox 40 source, uncompressed, then timed the unpack with Measure-Command { tar xf .\firefox-40.0.source.tar } in Powershell as described in that issue. Result 118 seconds. Which means I already have the fix since it didn't take close to 30 minutes.

And that I guess is bad news for us since I already had the fix when I got slow Pkg timings in the Discourse thread.

[AsafManela]

Thanks for fixing this.
I am teaching a class with about half the students using windows and this is generating some frustration with time to first package install at 10-15 minutes.

1. Which julia release is this expected to enter?
2. Any quick fixes I can share with the students in the meanwhile?

[StefanKarpinski]

Should already be in the 1.5.3 release.