First breakpoint is skipped on a remote development environment

[andyw8]

Describe the bug

Breakpoint skipped when running on a remote development environment

To Reproduce

1. Go to https://github.com/github/codespaces-rails to start with a new Rails app.

2. Choose Use This Template -> Open in a Codespace

3. Create the following in .vscode/launch.json

      {
       // Use IntelliSense to learn about possible attributes.
       // Hover to view descriptions of existing attributes.
       // For more information, visit: https://go.microsoft.com/fwlink/?linkid=830387
       "version": "0.2.0",
       "configurations": [
         {
           "type": "rdbg",
           "name": "Run the current file with rdbg",
           "useBundler": true,
           "request": "launch",
           "command": "ruby",
           "script": "${file}",
         },
       ]
   }

4. Create the following in test.rb.

   a=1
   binding.b
   binding.b

5. Ensure v0.1.0 of the vscode-rdbg extension is installed.

6. Switch to test.rb and choose "Run the current file with rdbg". Observe that it correctly stops at the first breakpoint.

7. Stop the debugger.

8. Add sleep 1 on a new line after a=1

9. Choose "Run the current file with rdbg" again.

10. Observe that it incorrectly skips the first breakpoint and stops at the second.

Your environment

• ruby -v: ruby 3.1.3p185 (2022-11-24 revision 1a6b16756e) [x86_64-linux]
• rdbg -v: rdbg 1.7.1

Expected behavior

It should stop at the first breakpoint.

[andyw8]

Some further findings on this:

It seems like a race condition. If I add sleep 0.1 before this line:

debug/lib/debug/server.rb

Line 350 in d7bf3b2

DEBUGGER__.debug{ "readline: #{msg.inspect}" }

then it stops at the first breakpoint.

I'm wondering if could relate to #131

Also:

• It doesn't occur when useTerminal is enabled.

(cc @st0012)

[andyw8]

Additionally, if I set this to false, it seems to illustrate that it does stop on the first breakpoint, but immediately continues.

[1, 4] in /workspaces/codespaces-rails/test.rb
     1| a = 1
     2| sleep 1
=>   3| binding.b
     4| binding.b
=>#0	<main> at /workspaces/codespaces-rails/test.rb:3
(rdbg:#debugger) eval $stdout.sync=true
[1, 4] in /workspaces/codespaces-rails/test.rb
     1| a = 1
     2| sleep 1
     3| binding.b
=>   4| binding.b