JRuby is making my VIM startup unbearable

2 minute read

TLDR: If you use vim-ruby and jruby you’re going to have a bad time. 2.5~ seconds to open or save a file kinda bad time. If you want to have your code properly checked on the version of ruby you are working with, tough. Other wise you can add let g:ruby_path in your .vimrc to configure which ruby build you use. Remember that rvm can change your ruby automatically. so be careful.

I run a VIM run-time like most probably do these days. Lots of plugins to make life a joy in my favourite terminal based text editor. I had it set up real nice. Airplane theme, nice modded power-line fonts, syntax checkers, file browsing, better tab and buffer bars, a really nice status bar, lovely colours. The works!

You don’t want to have to think about your text editor when you trying to work, to the point where it gets aggravating to me really quickly to have to do so. So when opening and saving a file is visibly really, really slow, like multiple seconds slow. It really starts to tick me off.

This starting happening to me a few months ago, and oddly it wasn’t consistent. I was busy though, so I put off looking at it in depth, again and again. Sometimes it would happen others times it wouldn’t. I had started to think it was one of the plugins so this morning I thought I would finally look at it, as it was working on porting a Ruby app from MRI to jruby and it was getting very annoying to wait so long to edit a gem file repeatedly.

Thanks to a quick google, I found that vim has an option --startuptime <file> to dump it’s startup timings in to a file! Great!

First let try no file:

$ vim --startuptime /tmp/vimstartup
132.137  000.010: --- VIM STARTED ---

Oh, sub second loading? That is how it should be!

Now with a ruby file from this project:

$ vim --startuptime /tmp/vimstartup config/routes.rb
$ cat /tmp/vimstartup
070.780  000.332: reading viminfo
070.807  000.027: setting raw mode
070.829  000.022: start termcap
070.895  000.066: clearing screen
2351.422  2278.069  2278.069: sourcing /usr/share/vim/vim74/ftplugin/ruby.vim
2352.217  000.456  000.456: sourcing /usr/share/vim/vim74/indent/ruby.vim
2354.229  001.773  001.773: sourcing /usr/share/vim/vim74/syntax/ruby.vim

“Bloody hell, 2 seconds to clear the screen? That can’t be right.” I thought. No, it isn’t right you buffoon, read it properly:

2351.422 2278.069 2278.069: sourcing /usr/share/vim/vim74/ftplugin/ruby.vim

Oh right, the plugin that runs ruby code to check it’s validity. vim-ruby

And then the penny drops. I’m using RVM! It switches the version of ruby in the environment depending on which project folder I am in. I am working on a jruby project now. THE JVM TAKES RELATIVELY EONS TO LOAD UP and I am doing it for each open and save.

Lets prove this I ran:

$ rvm use default (ruby-2.3.3 btw)
$ vim --startuptime /tmp/vimstartup
$ cat /tmp/vimstartup
131.720  060.401  060.401: sourcing /usr/share/vim/vim74/ftplugin/ruby.vim
200.410  000.002: --- VIM STARTED ---


Whist nice to prove, this doesn’t solve the problem. I want my startup times back. I can add let g:ruby_path <path> to my .vimrc in order to load a different ruby, but I lose the ability to check code on the version of ruby I am writing for. Unsure what to do about this right now. I could force the ruby to default before starting vim I guess? Yuk