chruby <version> is slow when internet is slow

[grosser]

I have ruby 2.6.5 installed locally and had an internet issue that made my connection slow, but not "dead", using cd or opening a new shell got slow and I dug in why, turns out it's chruby doing some kind of internet connection or dns.

time chruby 2.6.5

real    0m1.097s
user    0m0.058s
sys 0m0.019s

Can this get removed ? ... it seems unnecessary and it works fine when internet is completely down anyway.

[postmodern]

chruby.sh and auto.sh do not perform any kind of internet access. It's likely something else in your shell or possibly a rubygems plugin that's loaded by default. Try set -x in your shell or running the 2.6.5 ruby command under strace to try to find what internet access is happening and to what exactly.

[grosser]

switching was what caused the slowness, not running ruby ... set -x did not help and none of my network monitoring tools worked out .. so closing this until I have more info :)

[grosser]

reproduced it now:

  eval "$("$RUBY_ROOT/bin/ruby" - <<EOF
puts "export RUBY_ENGINE=#{defined?(RUBY_ENGINE) ? RUBY_ENGINE : 'ruby'};"
puts "export RUBY_VERSION=#{RUBY_VERSION};"
begin; require 'rubygems'; puts "export GEM_ROOT=#{Gem.default_dir.inspect};"; rescue LoadError; end
EOF
)"

causes it ... more specific: any call to ruby with a long body like this (with FOO it worked fine)

      eval "$("$RUBY_ROOT/bin/ruby" - <<EOF
puts "echo FOOFOOFOO=#{'ruby'};"
EOF
)"

... can we just avoid these calls to ruby when switching ruby somehow ?

[grosser]

for example replacing it with this works fine:

# /usr/local/Cellar/chruby/0.3.9/share/chruby/chruby.sh
  export RUBY_VERSION=$(basename $1)
  export RUBY_ENGINE=ruby
  export GEM_ROOT="$1/lib/ruby/gems/${RUBY_VERSION:0:3}.0"

... basically just need to redo some logic and bash and we are good to go :)

[postmodern]

chruby still has to query the ruby to figure out the RUBY_ENGINE, RUBY_VERSION, etc, which may not always be available from the directory name.

This implies that ruby is doing something with the network on startup? Could you run strace ruby -e "p 1" to see what it's calling out to? DNS? rubygems.org?

[grosser]

it's something about dns resolution being slow since that's atm the only thing that is weird on my machine (weird hotel internet)

was unable to use strace/dtruss since I got weird errors that lead me nowhere :(

codesign --remove-signature /usr/bin/ruby
/usr/bin/ruby: the codesign_allocate helper tool cannot be found or used

😞

I'd still think it would be nice to not call ruby when switching rubies as a general rabbit hole and loop avoidance (maybe only do it for simple cases somehow)

[postmodern]

Not a macOS user, but it might be that macOS is trying to verify the signature of ruby when it's ran? I thought macOS only did signature verification for .apps?

[grosser]

could totally be something like that, the sus thing is that it only happens for longer inputs

[postmodern]

sounds like something is being logged or phoned-home. Is this a work laptop? :raised_eyebrow:

[grosser]

yeah, totally possible. ... I guess just close if you think it's not a good idea or not feasible to remove the "calling ruby" part :)

[postmodern]

In 1.0.0 we will be relying less on RUBY_ENGINE and RUBY_VERSION to set the GEM_HOME/GEM_PATH, however those variables are exposed so people can set custom prompts that are ruby-version aware. The puts -> eval trick, while tricky, is the quickest way to get that data from ruby and into variables.

[postmodern]

PS: if you're really interested, there are off-the-shelf Wifi MITM hardware that would allow you to inspect all of the traffic going to/from the laptop. https://www.techtarget.com/searchsecurity/definition/Wi-Fi-Pineapple

[grosser]

I'm already way too deep in this rabbithole :D

On Wed, Dec 22, 2021 at 8:03 PM Postmodern @.***> wrote:

PS: if you're really interested, there are off-the-shelf Wifi MITM hardware that would allow you to inspect all of the traffic going to/from the laptop. https://www.techtarget.com/searchsecurity/definition/Wi-Fi-Pineapple

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[eregon]

FWIW in https://github.com/eregon/chruby/tree/do-no-set-gem-home I avoid the call to ruby, which also e.g. makes switching to JRuby faster.