Search $PATH for a binary rather than shelling out to `which` #1573

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merged 1 commit into from Dec 3, 2011

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@tenderlove
Collaborator

I'm trying to speed up startup time for rake environment (on rails). Creating subshells came up on my list, so I'm trying to eliminate them.

This patch changes Bundler to search the PATH environment variable rather than shelling out to which. The function isn't 100% perfect as it doesn't handle "./sudo" the same way the shell does, but our input for this function is known so I don't think it matters.

@sferik
Member
sferik commented Dec 3, 2011

Looks good. Thanks for your continued work on Rails performance improvements.

@sferik sferik merged commit 36c9f92 into bundler:master Dec 3, 2011
@wycats
Contributor
wycats commented Dec 3, 2011

@tenderlove - just curious... did you benchmark the difference (i.e. is the newer code actually faster than shelling out)?

@sferik
Member
sferik commented Dec 3, 2011

@fxn addressed your nitpick in 26fa77a.

@fxn
Collaborator
fxn commented Dec 3, 2011

@sferik that was fast :).

@tenderlove
Collaborator

@wycats

require 'rubygems'
require 'benchmark/ips'

def sand_which cmd
  `which #{cmd}`
end

def blair_which cmd
  if File.executable? cmd
    cmd
  else
    path = ENV['PATH'].split(File::PATH_SEPARATOR).find { |path|
      File.executable? File.join(path, cmd)
    }
    path && File.expand_path(cmd, path)
  end
end

Benchmark.ips do |x|
  x.report("sand") { sand_which 'sudo' }
  x.report("blair") { blair_which 'sudo' }
end
[aaron@higgins git]$ ruby lol.rb 
                sand      251.0 (±4.8%) i/s -       1265 in   5.051489s (cycle=23)
               blair     3222.0 (±8.2%) i/s -      16218 in   5.076616s (cycle=306)
[aaron@higgins git]$

It's over 10x faster. Probably because the one that shells out has to shell out.

@sleeper
sleeper commented Dec 10, 2011

That's a pitty: I proposed the same change on 2011-11-03 (#1516)... Today, nobody even had a look at it :(
Happy to see it merged by another channel, but kind of puzzled with the way mine has been handled ... Definitively not a way to encourage people to participate.

@sleeper sleeper referenced this pull request Dec 10, 2011
Closed

which: no sudo in ... #1321

@bfolkens

ENV['PATH'] is sometimes nil and breaks in a production environment I have with Passenger... Can we change it to ENV['PATH'].to_s or something to avoid that?

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