Speed up travis runtime.

[botandrose]

Vast majority of time is in bundle install, and the vast majority of
that is installing nokogiri. Parallelize bundle install, and use system
libraries for nokogiri installation.

[botandrose]

Strange, how do I get Travis to test this branch? I thought it tested all PRs automatically.

[aprescott]

This comment feels overly specific and probably doesn't need to be here.

[botandrose]

I've confirmed that setting BUNDLE_JOBS will give us the parallelization without requiring an override of the install command. Force pushed a new commit that addressed your two issues, and Travis appears to be testing this one! We should see a nice speedup.

[botandrose]

Nice speedup, indeed.

master:
Job Duration    Finished    Ruby
 530.1  4 min 16 sec    2 days ago  2.0.0
 530.2  4 min 15 sec    2 days ago  1.9.3
 530.3  6 min 14 sec    2 days ago  rbx-2
 530.4  3 min 26 sec    2 days ago  jruby-19mode

speed_up_travis:
Job Duration    Finished    Ruby
 535.1  2 min 32 sec    8 minutes ago   2.0.0
 535.2  3 min 7 sec 7 minutes ago   1.9.3
 535.3  6 min 16 sec    3 minutes ago   rbx-2
 535.4  4 min 11 sec    3 minutes ago   jruby-19mode

[botandrose]

MRIs are a clear win, but rbx seems unaffected, and jruby is slower! I investigated, and those numbers are red herrings. On this branch, rbx-2 failed to fetch a gem over the network on first try, so it needed to do a full rebundle. jruby-19mode failed two flaky specs on first try, so it did a retry of those specs. Neither of these things happened when travis last ran on master. This suggests its faster across the board, flaky specs and network notwithstanding.

[aprescott]

I think it's very unlikely that we'll not see a speedup from parallelising bundle installs (all else equal), so this seems good to me regardless! I actually thought that bundler did this by default using a reasonable job value for the system, but it seems not?

[botandrose]

Yeah, I would expect the jobs setting to be inferred, or to have a sensible default, but it is not. One must manually set jobs on each machine. I expect that future versions of bundler will have jobs set to something > 1 by default, but it is currently not the case.

[route]

What's the state of this?

[botandrose]

As far as I know, this is good to merge. The CI was green, but I just force-pushed a rebase to make sure we're up to date. However, looks like master was already failing. Doh.

[Kriechi]

I'm not sure about this. The latest TravisCI log shows:
$ bundle install --jobs=3 --retry=3

Should it be using 4 jobs, as suggested here, or is the output faulty?

[botandrose]

Interesting. I bet Travis has updated their default bundle command to take advantage of concurrency since this PR was submitted. I'll push another commit to remove BUNDLE_JOBS, since Travis appears to curating this setting now.

Otherwise, NOKOGIRI_USE_SYSTEM_LIBRARIES=true appears to be working:

Building nokogiri using system libraries.

[route]

@botandrose Yeah there are three tests in master that fail for now, because they aren't filtered out by capybara_skip. Let's wait till new window system will be merged in master and then merge your PR.

[route]

Thank you!