Deadlock after issuing `Net::HTTP.get` request and using a Ruby Debug breakpoint after the request

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#1,145 opened on May 3, 2023 2 comments 0 reactions 0 assignees View on GitHub

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Assessment

Difficulty: 3/5
Estimated time: 1-2 days
Newbie friendliness: 42/100

Issue type: Bug
Clarity: Clearly specified
Activity status: Stale
Tech stack: ruby
Domain: devtools

Research direction

Start with the reproduction script in test.rb and compare the behavior with net-http 0.2.0 and 0.3.0 or higher. Read lib/debug/thread_client.rb around lines 874 and 1233, along with the breakpoint and session paths in the stack trace; done means history navigation at the breakpoint no longer raises a deadlock.

Written by the indexing model from the issue text.

Description

We noticed a thread deadlock issue with Ruby debug after our net/http version changed from 0.2.0 to 0.3.0.

Screenshot 2023-05-03 at 13 13 18

When you are in the breakpoint after making any http request and you attempt to fetch your debug history (e.g. you arrow key up a few times), it crashes.

This error occurs in Ruby 3.1.3 which is using net-http (0.3.0). It does not occur in Ruby 3.1.2 (or earlier) which is using net-http (0.2.0).

Reproduction script (using net-http 0.3.0 or higher):

require "debug"
require "net/http"

Net::HTTP.get(URI.parse("https://google.com"))

binding.b

Stack trace:

["DEBUGGER Exception: .rbenv/versions/3.1.3/lib/ruby/gems/3.1.0/gems/debug-1.7.1/lib/debug/thread_client.rb:1233",
 #<fatal: No live threads left. Deadlock?
3 threads, 3 sleeps current:0x000000014a83b950 main thread:0x000000015a6048e0
* #<Thread:0x0000000100ec4d10 sleep_forever>
   rb_thread_t:0x000000015a6048e0 native:0x00000001faaf9b40 int:0

* #<Thread:0x000000010107e4a8@DEBUGGER__::SESSION@server .rbenv/versions/3.1.3/lib/ruby/gems/3.1.0/gems/debug-1.7.1/lib/debug/session.rb:177 sleep_forever>
   rb_thread_t:0x000000014a83b950 native:0x000000016f393000 int:0

* #<Thread:0x0000000104d64548@Timeout stdlib thread .rbenv/versions/3.1.3/lib/ruby/gems/3.1.0/gems/timeout-0.3.1/lib/timeout.rb:101 sleep_forever>
   rb_thread_t:0x000000014a9f1ce0 native:0x000000016f59f000 int:0

>,
 [".rbenv/versions/3.1.3/lib/ruby/gems/3.1.0/gems/debug-1.7.1/lib/debug/thread_client.rb:874:in `pop'",
  ".rbenv/versions/3.1.3/lib/ruby/gems/3.1.0/gems/debug-1.7.1/lib/debug/thread_client.rb:874:in `wait_next_action_'",
  ".rbenv/versions/3.1.3/lib/ruby/gems/3.1.0/gems/debug-1.7.1/lib/debug/thread_client.rb:856:in `wait_next_action'",
  ".rbenv/versions/3.1.3/lib/ruby/gems/3.1.0/gems/debug-1.7.1/lib/debug/thread_client.rb:320:in `suspend'",
  ".rbenv/versions/3.1.3/lib/ruby/gems/3.1.0/gems/debug-1.7.1/lib/debug/thread_client.rb:251:in `on_breakpoint'",
  ".rbenv/versions/3.1.3/lib/ruby/gems/3.1.0/gems/debug-1.7.1/lib/debug/breakpoint.rb:69:in `suspend'",
  ".rbenv/versions/3.1.3/lib/ruby/gems/3.1.0/gems/debug-1.7.1/lib/debug/breakpoint.rb:178:in `block in setup'",
  ".rbenv/versions/3.1.3/lib/ruby/gems/3.1.0/gems/debug-1.7.1/lib/debug/session.rb:2586:in `debugger'",
  "test.rb:6:in `<main>'"]]
.rbenv/versions/3.1.3/lib/ruby/gems/3.1.0/gems/debug-1.7.1/lib/debug/thread_client.rb:874:in `pop': No live threads left. Deadlock? (fatal)
3 threads, 3 sleeps current:0x000000014a83b950 main thread:0x000000015a6048e0
* #<Thread:0x0000000100ec4d10 sleep_forever>
   rb_thread_t:0x000000015a6048e0 native:0x00000001faaf9b40 int:0

* #<Thread:0x000000010107e4a8@DEBUGGER__::SESSION@server .rbenv/versions/3.1.3/lib/ruby/gems/3.1.0/gems/debug-1.7.1/lib/debug/session.rb:177 sleep_forever>
   rb_thread_t:0x000000014a83b950 native:0x000000016f393000 int:0

* #<Thread:0x0000000104d64548@Timeout stdlib thread .rbenv/versions/3.1.3/lib/ruby/gems/3.1.0/gems/timeout-0.3.1/lib/timeout.rb:101 sleep_forever>
   rb_thread_t:0x000000014a9f1ce0 native:0x000000016f59f000 int:0

	from .rbenv/versions/3.1.3/lib/ruby/gems/3.1.0/gems/debug-1.7.1/lib/debug/thread_client.rb:874:in `wait_next_action_'
	from .rbenv/versions/3.1.3/lib/ruby/gems/3.1.0/gems/debug-1.7.1/lib/debug/thread_client.rb:856:in `wait_next_action'
	from .rbenv/versions/3.1.3/lib/ruby/gems/3.1.0/gems/debug-1.7.1/lib/debug/thread_client.rb:320:in `suspend'
	from .rbenv/versions/3.1.3/lib/ruby/gems/3.1.0/gems/debug-1.7.1/lib/debug/thread_client.rb:251:in `on_breakpoint'
	from .rbenv/versions/3.1.3/lib/ruby/gems/3.1.0/gems/debug-1.7.1/lib/debug/breakpoint.rb:69:in `suspend'
	from .rbenv/versions/3.1.3/lib/ruby/gems/3.1.0/gems/debug-1.7.1/lib/debug/breakpoint.rb:178:in `block in setup'
	from .rbenv/versions/3.1.3/lib/ruby/gems/3.1.0/gems/debug-1.7.1/lib/debug/session.rb:2586:in `debugger'
	from test.rb:6:in `<main>'

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