Rails console hangs with downward-pointing triangle

[chrisbouchard]

I know this is an old issue, but I'm running into it and I've tried the fix listed in the README. When I run inf-ruby-console-auto (or in my original case, try to use Robe), the console hangs. It shows the first two lines of output from Rails, but instead of a prompt just shows a blue, downward-pointing triangle. I can type but the console is unresponsive.

Is there any chance this is a new bug? Or have I just missed something in my setup?

$ ruby --version
ruby 3.0.1p64 (2021-04-05 revision 0fb782ee38) [x86_64-linux]
$ bin/rails --version
Rails 6.1.3.2
$ bin/rails console -- --version
Running via Spring preloader in process 17046
Loading development environment (Rails 6.1.3.2)
irb 1.3.5 (2021-04-03)
$ cat ~/.irbrc
IRB.conf[:USE_MULTILINE] = false if ENV['INSIDE_EMACS']
$ emacs --version
GNU Emacs 27.2
Copyright (C) 2021 Free Software Foundation, Inc.
GNU Emacs comes with ABSOLUTELY NO WARRANTY.
You may redistribute copies of GNU Emacs
under the terms of the GNU General Public License.
For more information about these matters, see the file named COPYING.

(pkg-info-package-version "inf-ruby")
20220203.153

[chrisbouchard]

Just tried updating a couple things, and I still run into this with

$ ruby --version
ruby 3.0.3p157 (2021-11-24 revision 3fb7d2cadc) [x86_64-linux]
$ bin/rails --version
Rails 6.1.4.6
$ bin/rails console -- --version
Running via Spring preloader in process 71796
Loading development environment (Rails 6.1.4.6)
irb 1.3.5 (2021-04-03)

[dgutov]

Hi!

Any chance you started the console outside of Emacs first (after which Spring has cached its environment), and then started it inside Emacs?

You can try removing Spring (at least for the duration of troubleshooting) and then repeating the attempt.

If that fails, can you try stepping through inf-ruby-console-rails and see whether the inf-ruby--irb-needs-nomultiline-p returns t?

[dgutov]

To step through the function, move to its definition with M-x find-function, then press C-u C-M-x (to edebug-defun).

Then repeat the usual scenario in Emacs, you should land in the interactive debugging at the beginning of that function. Step through it by repeatedly pressing SPC.

To undo instrumentation, press C-M-x when within the function definition again (but without C-u).

[chrisbouchard]

I've removed Spring as a dependency, and confirmed that both bin/rails console and inf-ruby-console-auto start up without the Spring message. I've also debugged the inf-ruby-console-rails function as requested and can confirm that inf-ruby--irb-needs-nomultiline-p returns true and the -- --no-multiline part is being included in the command. However, the issue persists.

[dgutov]

That's odd.

I have just tried this in a newly created Rails project, and it worked fine (no triangle).

Rails 6.1.4.6, Ruby 3.0.2, IRB 1.3.5.

More importantly, you're also saying you have IRB.conf[:USE_MULTILINE] = false if ENV['INSIDE_EMACS'] inside ~/.irbrc. That should solve the problem by itself (and it does, in my testing), even if I comment our the respective code in inf-ruby-console-rails.

There might be something in your project that counteracts this setting.

Try creating a new Rails project. Does it exhibit the same problem?

Also try Ruby 3.0.2 maybe (I don't have the time to compile a different version ATM), but the chances of that helping are really slim.

[chrisbouchard]

No luck on my end, I'm afaid. I've upgraded to the latest Ruby and Rails — 3.1.1 and 7.0.2.2, respectively. I've created two brand new Rails projects:

• One with rails new --api --database=postgresql, because those are the options I want for my project, and
• One with rails new, just to eliminate variables.

In both new projects I still get the blue triangle when I run inf-ruby-console-auto. :slightly_frowning_face:

I've doubly verified that the console is getting the --multiline flag.

$ pgrep -af rails
31311 /home/chris/.homesick/repos/rbenv/versions/3.1.1/bin/ruby bin/rails console -e development -- --nomultiline

And I've double-checked that my .irbrc file has the workaround.

$ cat ~/.irbrc
IRB.conf[:USE_MULTILINE] = false if ENV['INSIDE_EMACS']

Here are the new package versions in case it matters.

$ ruby --version
ruby 3.1.1p18 (2022-02-18 revision 53f5fc4236) [x86_64-linux]
$ bin/rails --version
Rails 7.0.2.2
$ bin/rails console -- --version
Loading development environment (Rails 7.0.2.2)
irb 1.4.1 (2021-12-25)

[chrisbouchard]

Oh! But I just tried inf-ruby and that used my global Ruby 3.0.2 and it worked. So maybe something did break in Ruby 3.0.3+.

[dgutov]

The next step would be to see whether any of the loaded gems modify [:USE_MULTILINE] as well.

But if you have a sample project ready which exhibits the problem, please zip it up and attach to this conversation, I'll take a look.

[dgutov]

But I just tried inf-ruby and that used my global Ruby 3.0.2 and it worked.

M-x inf-ruby-console-auto also worked?

[chrisbouchard]

I'm testing that now. Just had to do some rbenv juggling to install Rails.

[chrisbouchard]

Yes, inf-ruby-console-auto also works with 3.0.2! So something's not working in 3.0.1, 3.0.3, and 3.1.x, as far as I can tell. But I'm happy to stick with 3.0.2 for now.

[dgutov]

Interesting. I'll check it out, thanks.

To be sure, you can still upload that sample project: after all, the problem could be a combination of Ruby 3.0.3's behavior and something in the project configuration.

[chrisbouchard]

Ok, will do. :+1:

One other thing — I'm just baffled because I can't see any meaningful difference between the irb sessions in 3.1.1 and 3.0.2.

test-rails-3.1.1$ bin/rails console -- --nomultiline
irb(main):001:0> puts 'Hello'
Hello
=> nil
irb(main):002:0>

test-rails-3.0.2$ bin/rails console -- --nomultiline
irb(main):001:0> puts 'Hello'
Hello
=> nil
irb(main):002:0>

Same prompt, same ANSI coloring (just the nil in cyan, the rest default). Neither is using the new syntax highlighting or code completion.

[chrisbouchard]

The two test projects I've been using:

• https://github.com/chrisbouchard/inf-ruby-test-rails-3.1.1 — Hangs with blue triangle
• https://github.com/chrisbouchard/inf-ruby-test-rails-3.0.2 — Seems to work just fine

[dgutov]

Just a quick question: does adding --nosingleline and/or --noreadline help things?

I.e.

diff --git a/inf-ruby.el b/inf-ruby.el
index a3f5245..d898044 100755
--- a/inf-ruby.el
+++ b/inf-ruby.el
@@ -1066,7 +1066,7 @@ automatically."
              ;; Note: this only has effect in Rails < 5.0 or >= 5.1.4
              ;; https://github.com/rails/rails/pull/29010
              (when (inf-ruby--irb-needs-nomultiline-p)
-               " -- --nomultiline"))
+               " -- --nomultiline --nosingleline --noreadline"))
      "rails")))

 (defun inf-ruby-console-rails-env ()

Press C-M-x to re-evaluate the definition after editing.

[chrisbouchard]

I'll just mention one other thing that I hope isn't relevant. My system ruby is 3.0.2 (Fedora 35). I've been using rbenv for all my development — even for 3.0.2 — so I don't need root to install packages. That's why inf-ruby used 3.0.2 when I ran it outside any project directory. When I ran inf-ruby-console-auto, Rails used ruby 3.0.2 installed via rbenv. So it works either way, but I'm just noticing that it breaks in any version that doesn't match my system ruby.

[chrisbouchard]

Yes, adding all those flags seems to fix the issue. I get an irb prompt in inf-ruby-console-auto even in 3.1.1. :tada:

[dgutov]

FWIW, I also use rbenv. And Ubuntu 20.04.

Yes, adding all those flags seems to fix the issue. I get an irb prompt in inf-ruby-console-auto even in 3.1.1.

Nice. Please try removing each of them in turn to see which of the flags was necessary. Maybe both, but that's doubtful.

[chrisbouchard]

It looks like --nomultiline --noreadline does it for me, at least enough to get past the blue triangle to a prompt, even without ~/.irbrc. :+1:

Edit to add: --nomultiline --nosingleline also seems to work.

[dgutov]

Ah, what I missed is that --nosingleline and --noreadline are basically the same option now, and both disable the use of Readline module.

So it's probably dependent on how Ruby was compiled rather on a particular version used. And I couldn't repro this with Ruby 3.0.3 now.

If you have any further interest in finding out the reason, evaluating the following should help: IRB.CurrentContext.io

Here, it prints ReadlineInputMethod with ext/readline 8.0 inside my Emacs, in inf-ruby, so apparently it's able to work inside Emacs at least with my particular configuration.

Try running bin/rails console -- --nomultiline outside Emacs and evaluating the same expression. Perhaps it will print a different version of readline or some substitute.

Either way, it seems adding --nosingleline (or --noreadline for backward compat) in several places inside inf-ruby seems like a good idea. But it would be nice to document the particular reasons.

[chrisbouchard]

I see you've already closed this issue, but I got a chance to try out what you suggested with IRB.CurrentContext.io and thought I'd share my results.

Both my rails test projects (ruby 3.0.2 and 3.1.1) report the same.

$ bin/rails console -- --nomultiline
Loading development environment (Rails 7.0.2.2)
irb(main):001:0> IRB.CurrentContext.io
=> ReadlineInputMethod with Reline 0.3.1
irb(main):002:0> 

Even irb reports that inside of a rails project, because rbenv is picking up the version in the .ruby-version file and using that installed version rather than the system version.

Outside of a rails project, irb reports differently.

$ irb --nomultiline
irb(main):001:0> IRB.CurrentContext.io
=> ReadlineInputMethod with ext/readline 8.1
irb(main):002:0>

And for the record, when run with --noreadline (or --nosingleline) I get different results yet.

$ irb --nomultiline --noreadline
irb(main):001:0> IRB.CurrentContext.io
=> StdioInputMethod
irb(main):002:0>
$ bin/rails console -- --nomultiline --noreadline
Loading development environment (Rails 7.0.2.2)
irb(main):001:0> IRB.CurrentContext.io
=> StdioInputMethod

Here I also get the same results when using the system ruby.

So it does seem to be about system vs. rbenv, at least for picking the input method. inf-ruby works fine with ReadlineInputMethod with ext/readline 8.1 (and of course StdioInputMethod) but does not work with ReadlineInputMethod with Reline 0.3.1 regardless of ruby version.

From some quick research, it looks like additional install-time arguments are needed to make rbenv use the system readline library. I'm curious to give that a try and see if I get different results.

Edit: I installed readline-devel in Fedora and now rbenv install picks up and uses the system readline. Once it does, inf-ruby-console-auto works with just --nomultiline.

[dgutov]

I see you've already closed this issue, but I got a chance to try out what you suggested with IRB.CurrentContext.io and thought I'd share my results.

Thanks! Now we know that it is indeed the lack of Readline that caused the problem, and Reline's incompatibility with running inside Emacs.

Edit: I installed readline-devel in Fedora and now rbenv install picks up and uses the system readline. Once it does, inf-ruby-console-auto works with just --nomultiline.

That's what I wanted to say: as long as the -dev package is installed (in my distro), rbenv install doesn't require any extra arguments. That blog post is a little old, so no surprise that it's off in some details.

And the system Ruby is different because it's been compiled on another computer already, so it doesn't depend on the -dev[el] package.

[ErikSchierboom]

Passing -- --noreadline to rails console worked like a charm! Thanks a lot.

[dgutov]

FWIW, using Ruby built without libreadline might still not be a good idea.

If your project is large enough, completion can be slow with rb-readline: https://github.com/dgutov/robe/issues/139