From: Charles Oliver Nutter <headius@...>
Date: 2011-11-29T19:55:25+09:00
Subject: [ruby-core:41389] Re: [Backport93 - Backport #5621] Please backport thread-safe autoloading patch

On Tue, Nov 29, 2011 at 4:43 AM, Charles Oliver Nutter
<headius@headius.com> wrote:
> I think an additional warning about doing requires lazily might be
> useful...perhaps any require that happens on some non-main thread that
> *isn't* in response to a require should elicit a warning? Or perhaps
> when we detect concurrent non-autooad requires (i.e. two threads doing
> separate requires at the same time, regardless of the files they're
> loading) we should warn?

Here's an impl of the latter. The first thread to start requiring
acquires a lock, and subsequent threads that attempt to require simply
warn. It's primitive, since it warns on those other threads for
*every* require including the topmost, but it demonstrates the idea.

https://gist.github.com/1404402

Example uses:


system ~/projects/jruby $ jruby -e "Thread.new { require 'fileutils'
}; require 'optparse'"
:1 warning: concurrent require of `fileutils` detected
/Users/headius/projects/jruby/lib/ruby/1.8/fileutils.rb:979 warning:
concurrent require of `etc` detected

system ~/projects/jruby $ jruby -e "Thread.new { require 'fileutils'
}; Thread.new { require 'optparse' }"
:1 warning: concurrent require of `optparse` detected

system ~/projects/jruby $ jruby -e "Thread.new { require 'fileutils'
}.join; require 'optparse'"

system ~/projects/jruby $