REPL prints next prompt without printing result of previous command

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#1,021 opened on Sep 28, 2023 3 comments 0 reactions 0 assignees View on GitHub

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Assessment

Difficulty: 4/5
Estimated time: 3-5 days
Newbie friendliness: 30/100

Issue type: Bug
Clarity: Needs clarification
Activity status: Stale
Tech stack: ruby
Domain: cli, devtools

Research direction

Start by reproducing the intermittent REPL behavior with Ruby 3.2.2, rdbg 1.8.0, and the reported debug revision, focusing on next, step, whereami, and expression evaluation. Use the examples in the issue to investigate why prompts appear without results; done means each command's result is printed before the next prompt and the behavior has a reliable regression test.

Written by the indexing model from the issue text.

Description

Your environment

ruby -v:

~/wk/mos % ruby -v
ruby 3.2.2 (2023-03-30 revision e51014f9c0) [arm64-darwin22]

rdbg -v:

~/wk/mos % rdbg -v
rdbg 1.8.0
{:mode=>:start, :no_color=>nil, :no_reline=>true}

I should point out that I am loading debug from the github repo at revision 3d0f4e3225c4 after the discussion in #1000:

~/wk/mos % bundle show debug
~/.rbenv/versions/3.2.2/lib/ruby/gems/3.2.0/bundler/gems/debug-3d0f4e3225c4

Describe the bug
The REPL intermittently gets stuck in a state where it will not print the result of commands, even though it seems that they are continuing to be processed.

To Reproduce

I don't have a reliable repro process, but I will note that I have noticed this behaviour after sending the next command, and also after trying to evaluate an instance method at a breakpoint. Examples in the Additional context section below. Sending puts '' to the repl sometimes seems to help bring it back to the expected behaviour, but not always.

Expected behavior
I expect the REPL to print the result of each command before printing the next prompt.

Additional context

Here's an example where I tried to run `next` multiple times, and I encountered this behaviour. I was eventually able to shake it loose by running `puts 'hello'`, and it appears that the debugger had advanced forward in the background, even though it had not provided feedback.

[90, 99] in ~/wk/mos/app/models/contract.rb
    90|   end
    91|
    92|   private
    93|
    94|   def validate_initiated_to_profile_role
=>  95|     debugger
    96|     return unless initiated_to_profile.has_role?(:owner)
    97|
    98|     errors.add(:initiated_to_profile, "cannot be an owner")
    99|   end
=>#0	Contract#validate_initiated_to_profile_role at ~/wk/mos/app/models/contract.rb:95
  #1	block {|target=#<Contract:0x000000010e0c64a8 id: nil, ve..., value=nil, block=nil|} in make_lambda at ~/.rbenv/versions/3.2.2/lib/ruby/gems/3.2.0/gems/activesupport-7.0.8/lib/active_support/callbacks.rb:400
  # and 92 frames (use `bt' command for all frames)
(rdbg) next
(rdbg) next
(rdbg) next
(rdbg) whereami
(rdbg) frame 0
(rdbg) bt
(rdbg) puts 'hello'
hello
nil
(rdbg) whereami
[94, 103] in ~/wk/mos/app/models/contract.rb
    94|   def validate_initiated_to_profile_role
    95|     debugger
    96|     return unless initiated_to_profile.has_role?(:owner)
    97|
    98|     errors.add(:initiated_to_profile, "cannot be an owner")
=>  99|   end
   100|
   101|   def invalid_activity_groups
   102|     Activity::Kind::Groups::Invalid.new(contract: self).result
   103|   end
=>#0	Contract#validate_initiated_to_profile_role at ~/wk/mos/app/models/contract.rb:99 #=> #<ActiveModel::Error attribute=initiated_...
  #1	block {|target=#<Contract:0x000000010e0c64a8 id: nil, ve..., value=nil, block=nil|} in make_lambda at ~/.rbenv/versions/3.2.2/lib/ruby/gems/3.2.0/gems/activesupport-7.0.8/lib/active_support/callbacks.rb:400
  # and 92 frames (use `bt' command for all frames)

Here's another case where using `puts` was able to break me out:

[231, 240] in ~/.rbenv/versions/3.2.2/lib/ruby/gems/3.2.0/gems/administrate-0.19.0/app/controllers/administrate/application_controller.rb
   231|       @resource_resolver ||=
   232|         Administrate::ResourceResolver.new(controller_path)
   233|     end
   234|
   235|     def translate_with_resource(key)
=> 236|       t(
   237|         "administrate.controller.#{key}",
   238|         resource: resource_resolver.resource_title,
   239|       )
   240|     end
=>#0	Administrate::ApplicationController#translate_with_resource(key="create.success") at ~/.rbenv/versions/3.2.2/lib/ruby/gems/3.2.0/gems/administrate-0.19.0/app/controllers/administrate/application_controller.rb:236
  #1	Dashboard::ApplicationController#create at ~/wk/mos/app/controllers/dashboard/application_controller.rb:36
  # and 74 frames (use `bt' command for all frames)
(rdbg) key
"create.success"
(rdbg) "administrate.controller.#{key}"
(rdbg) next
(rdbg) whereami
(rdbg) puts ''

nil
(rdbg) whereami
[235, 244] in ~/.rbenv/versions/3.2.2/lib/ruby/gems/3.2.0/gems/administrate-0.19.0/app/controllers/administrate/application_controller.rb
   235|     def translate_with_resource(key)
   236|       t(
   237|         "administrate.controller.#{key}",
   238|         resource: resource_resolver.resource_title,
   239|       )
=> 240|     end
   241|
   242|     def show_search_bar?
   243|       dashboard.attribute_types_for(
   244|         dashboard.all_attributes,
=>#0	Administrate::ApplicationController#translate_with_resource(key="create.success") at ~/.rbenv/versions/3.2.2/lib/ruby/gems/3.2.0/gems/administrate-0.19.0/app/controllers/administrate/application_controller.rb:240 #=> "Contract was successfully created."
  #1	Dashboard::ApplicationController#create at ~/wk/mos/app/controllers/dashboard/application_controller.rb:36
  # and 74 frames (use `bt' command for all frames)

Here's another example where using `puts` did not help, but it did finally shake loose when i sent only `;`.

[22, 31] in ~/wk/mos/app/controllers/dashboard/application_controller.rb
    22|     end
    23|
    24|     def handle_create
    25|       resource = new_resource(resource_params)
    26|       authorize_resource(resource)
=>  27|       debugger
    28|       resource.save
    29|     end
    30|
    31|     def create
=>#0	Dashboard::ApplicationController#handle_create at ~/wk/mos/app/controllers/dashboard/application_controller.rb:27
  #1	Dashboard::ApplicationController#create at ~/wk/mos/app/controllers/dashboard/application_controller.rb:32
  # and 74 frames (use `bt' command for all frames)
(rdbg) resource
#<Facility:0x000000010f93b740 id: nil, name: "Slow Dock", created_at: nil, updated_at: nil, tenant_id: nil>
(rdbg) resource.save
true
(rdbg) resource.tap(&:save)
(rdbg) puts
(rdbg) puts;
(rdbg) puts ''
(rdbg) whereami
(rdbg) ;
nil

Another case where `puts` didn't work once, but seemed to work later

[44, 53] in ~/wk/mos/app/controllers/dashboard/vessels_controller.rb                                                                            |  ETA: 00:01:37
    44|     # for more information
    45|
    46|     private
    47|
    48|     def filter_resources(resources, search_term:)
=>  49|       debugger if search_term.present?
    50|       Administrate::Search.new(
    51|         resources,
    52|         dashboard,
    53|         search_term
=>#0	Dashboard::VesselsController#filter_resources(resources=[#<Vessel:0x000000012617c088 id: 750, nam..., search_term="pending_activity:winterize") at ~/wk/mos/app/controllers/dashboard/vessels_controller.rb:49
  #1	Administrate::ApplicationController#index at ~/.rbenv/versions/3.2.2/lib/ruby/gems/3.2.0/gems/administrate-0.19.0/app/controllers/administrate/application_controller.rb:8
  # and 77 frames (use `bt' command for all frames)
(rdbg) next
(rdbg) step
(rdbg) puts
(rdbg) ;
(rdbg) whereami
(rdbg) puts '';

nil
(rdbg) whereami
[174, 183] in ~/.rbenv/versions/3.2.2/lib/ruby/gems/3.2.0/gems/administrate-0.19.0/app/controllers/administrate/application_controller.rb
   174|     def sorting_params
   175|       Hash.try_convert(request.query_parameters[resource_name]) || {}
   176|     end
   177|
   178|     def dashboard
=> 179|       @dashboard ||= dashboard_class.new
   180|     end
   181|
   182|     def requested_resource
   183|       @requested_resource ||= find_resource(params[:id]).tap do |resource|

I suspect this is a race condition of some kind. If I notice any more patterns, I'll update this issue. If anyone has any troubleshooting or reproduction suggestions, let me know.

Thanks

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