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ruby
remote debugger failing on first hit with puma
Your environment
ruby -v: 3.3.5rdbg -v: 1.9.2
Describe the bug When hitting breakpoint via placing "debugger" into source code, and connecting with remote debugger, with sinatra controller and puma web server in local docker container, first time when "debugger" is hit will fail, as described below
For example, Puma started freshly serving sinatra app in local docker container
33| def some_method_called_via_puma_via_sinatra_controller
=> 34| debugger
35| some logic...
37| end
38|
(rdbg:remote) n
# No sourcefile available for /usr/local/bundle/gems/puma-6.4.2/lib/puma/single.rb
Stop by SIGURG
(rdbg:remote) n
# it looks like it tries to step in code, but in reality context is lost
(rdbg:remote) n
[1, 7] in $(Gem)/rack-2.2.9/lib/rack/file.rb
1| # frozen_string_literal: true
2|
3| require_relative 'files'
4|
=> 5| module Rack
6| File = Files
7| end
(rdbg:remote) c
Thus only way to end to proceed is to hit "continue", since control flow has jumped into some odd place, and now, after this failure when doing same request again, debugger works as espected (i.e. does not hit this "SIGURG" which seems to break thing).
Makes usage rather irritating since after every modify of code (and restart of web server thus), have to first hit debugger "cold", and failing, and hitting continue, and now it seems to be "hot", and can actually succeed.
To Reproduce
- Local docker container
- running sinatra app with puma on it
- setting up remote debugger
- adding breakpoint via placing "debugger" into code
- launching app on container
- performing some request hitting "debugger" put in code
- connect remote debugger to process => fails on first time, if hitting continue, and retrying request it works as expected
Expected behavior It would not fail on first time, since it makes debugging few cases difficult.
Additional context Issue has been there for a while, i.e. it has had this failure always for me with this debug gem
You mean that the "fail" is showing the "# No sourcefile available for /usr/local/bundle/gems/puma-6.4.2/lib/puma/single.rb " message, right?
I'm not sure but /usr/local/bundle/gems/puma-6.4.2/lib/puma/single.rb is available on the container?
I figured out that in order to make thing work is
- add "debugger" statement into desired place
- let "rerun" logic to restart app in container (thus any existing remote debugger session will be killed)
- attach remote debugger to app in aonther shell => it opens debugger console => hit continue on it
- Do relevant things to trigger breakpoint => when "debugger" is hit it activaves console session in remote debug session started in step (3) => it seems to work as expected
However, this sequence fails
- add "debugger" statement into desired place
- let "rerun" logic to restart app in container (thus any existing remote debugger session will be killed)
- Do relevant things to trigger breakpoint => it tells that it's waiting for remote debugger in stdout of app
- attach remote debugger to app in aonther shell => console opens => seems to be in right place => but after trying to do anything, it hits issue described in original description => thus does not actually work => hitting continue is only option possibly
- Do relevant things to trigger breakpoint again => when "debugger" is hit it activaves console session in remote debug session started in step (4) => this time it seems to work as expected
I'm able to reproduce this but without anything in docker.
The procedure is:
- add a
debuggerto a controller action
$ export RUBY_DEBUG_OPEN="true"
$ export RUBY_DEBUG_LAZY="true"
$ bin/rails s
- navigate browser to the controller action, server emits
DEBUGGER: Debugger can attach via UNIX domain socket (/var/folders/3j/9z86x6zx41v8408k3kjv_0y00000gn/T/rdbg-501/rdbg-82033) DEBUGGER: wait for debugger connection... - in a new terminal,
rdbg --attach
Additionally, the behavior I'm seeing on the first run is characterized by the output being from "the previous command" rather than the current command. Hopefully this demonstrates what I'm seeing:
The lines with numbers after the prompt should cause the debugger to evaluate the number and show the result (the same number). Instead, the results are off-by-one.
- input:
2, output: a partial stack trace - input:
3, output:2 - input:
4, output:3 - input:
5, output:4
Probably because of this off-by-one bug, I'm often unable to actually continue and have to pkill -QUIT the rdbg process. You can see that happened in this screenshot too. If I have to manually QUIT rdbg, I have to kill -KILL the rails server because it goes completely unresponsive -- I'm not particularly surprised by this, but it's further evidence that the debug socket is in disrepair.
> ruby -v
ruby 3.3.0 (2023-12-25 revision 5124f9ac75) [arm64-darwin24]
> rdbg -v
rdbg 1.10.0
Our Gemfile.lock
GEM
remote: https://rubygems.org/
specs:
actioncable (6.1.7.6)
actionpack (= 6.1.7.6)
activesupport (= 6.1.7.6)
nio4r (~> 2.0)
websocket-driver (>= 0.6.1)
actionmailbox (6.1.7.6)
actionpack (= 6.1.7.6)
activejob (= 6.1.7.6)
activerecord (= 6.1.7.6)
activestorage (= 6.1.7.6)
activesupport (= 6.1.7.6)
mail (>= 2.7.1)
actionmailer (6.1.7.6)
actionpack (= 6.1.7.6)
actionview (= 6.1.7.6)
activejob (= 6.1.7.6)
activesupport (= 6.1.7.6)
mail (~> 2.5, >= 2.5.4)
rails-dom-testing (~> 2.0)
actionpack (6.1.7.6)
actionview (= 6.1.7.6)
activesupport (= 6.1.7.6)
rack (~> 2.0, >= 2.0.9)
rack-test (>= 0.6.3)
rails-dom-testing (~> 2.0)
rails-html-sanitizer (~> 1.0, >= 1.2.0)
actiontext (6.1.7.6)
actionpack (= 6.1.7.6)
activerecord (= 6.1.7.6)
activestorage (= 6.1.7.6)
activesupport (= 6.1.7.6)
nokogiri (>= 1.8.5)
actionview (6.1.7.6)
activesupport (= 6.1.7.6)
builder (~> 3.1)
erubi (~> 1.4)
rails-dom-testing (~> 2.0)
rails-html-sanitizer (~> 1.1, >= 1.2.0)
activejob (6.1.7.6)
activesupport (= 6.1.7.6)
globalid (>= 0.3.6)
activemodel (6.1.7.6)
activesupport (= 6.1.7.6)
activerecord (6.1.7.6)
activemodel (= 6.1.7.6)
activesupport (= 6.1.7.6)
activestorage (6.1.7.6)
actionpack (= 6.1.7.6)
activejob (= 6.1.7.6)
activerecord (= 6.1.7.6)
activesupport (= 6.1.7.6)
marcel (~> 1.0)
mini_mime (>= 1.1.0)
activesupport (6.1.7.6)
concurrent-ruby (~> 1.0, >= 1.0.2)
i18n (>= 1.6, < 2)
minitest (>= 5.1)
tzinfo (~> 2.0)
zeitwerk (~> 2.3)
ast (2.4.2)
autoprefixer-rails (10.4.16.0)
execjs (~> 2)
awesome_print (1.9.2)
aws-eventstream (1.3.0)
aws-partitions (1.880.0)
aws-sdk-autoscaling (1.102.0)
aws-sdk-core (~> 3, >= 3.188.0)
aws-sigv4 (~> 1.1)
aws-sdk-core (3.190.2)
aws-eventstream (~> 1, >= 1.3.0)
aws-partitions (~> 1, >= 1.651.0)
aws-sigv4 (~> 1.8)
jmespath (~> 1, >= 1.6.1)
aws-sdk-ec2 (1.433.0)
aws-sdk-core (~> 3, >= 3.188.0)
aws-sigv4 (~> 1.1)
aws-sdk-kms (1.76.0)
aws-sdk-core (~> 3, >= 3.188.0)
aws-sigv4 (~> 1.1)
aws-sdk-rds (1.211.0)
aws-sdk-core (~> 3, >= 3.188.0)
aws-sigv4 (~> 1.1)
aws-sdk-s3 (1.142.0)
aws-sdk-core (~> 3, >= 3.189.0)
aws-sdk-kms (~> 1)
aws-sigv4 (~> 1.8)
aws-sigv4 (1.8.0)
aws-eventstream (~> 1, >= 1.0.2)
base64 (0.2.0)
bcrypt (3.1.20)
bigdecimal (3.1.5)
bootsnap (1.17.1)
msgpack (~> 1.2)
bootstrap-sass (3.4.1)
autoprefixer-rails (>= 5.2.1)
sassc (>= 2.0.0)
browser (2.5.3)
builder (3.2.4)
coderay (1.1.3)
coffee-rails (5.0.0)
coffee-script (>= 2.2.0)
railties (>= 5.2.0)
coffee-script (2.4.1)
coffee-script-source
execjs
coffee-script-source (1.12.2)
colored (1.2)
combine_pdf (1.0.26)
matrix
ruby-rc4 (>= 0.1.5)
concurrent-ruby (1.2.3)
connection_pool (2.4.1)
crass (1.0.6)
date (3.3.4)
debug (1.10.0)
irb (~> 1.10)
reline (>= 0.3.8)
digest (3.1.1)
docile (1.4.0)
domain_name (0.6.20240107)
dotenv (3.1.2)
dotenv-rails (3.1.2)
dotenv (= 3.1.2)
railties (>= 6.1)
drb (2.2.0)
ruby2_keywords
e2mmap (0.1.0)
erubi (1.12.0)
et-orbi (1.2.7)
tzinfo
ethon (0.16.0)
ffi (>= 1.15.0)
execjs (2.9.1)
factory_bot (6.4.5)
activesupport (>= 5.0.0)
faraday (1.10.3)
faraday-em_http (~> 1.0)
faraday-em_synchrony (~> 1.0)
faraday-excon (~> 1.1)
faraday-httpclient (~> 1.0)
faraday-multipart (~> 1.0)
faraday-net_http (~> 1.0)
faraday-net_http_persistent (~> 1.0)
faraday-patron (~> 1.0)
faraday-rack (~> 1.0)
faraday-retry (~> 1.0)
ruby2_keywords (>= 0.0.4)
faraday-em_http (1.0.0)
faraday-em_synchrony (1.0.0)
faraday-excon (1.1.0)
faraday-httpclient (1.0.1)
faraday-multipart (1.0.4)
multipart-post (~> 2)
faraday-net_http (1.0.1)
faraday-net_http_persistent (1.2.0)
faraday-patron (1.0.0)
faraday-rack (1.0.0)
faraday-retry (1.0.3)
ffi (1.17.0)
ffi (1.17.0-aarch64-linux-gnu)
ffi (1.17.0-arm-linux-gnu)
ffi (1.17.0-arm64-darwin)
ffi (1.17.0-x86-linux-gnu)
ffi (1.17.0-x86_64-darwin)
ffi (1.17.0-x86_64-linux-gnu)
firefly_server (0.1.7)
listen (~> 3.1)
fugit (1.9.0)
et-orbi (~> 1, >= 1.2.7)
raabro (~> 1.4)
geocodio (3.0.0)
json
globalid (1.2.1)
activesupport (>= 6.1)
http-cookie (1.0.5)
domain_name (~> 0.5)
i18n (1.14.1)
concurrent-ruby (~> 1.0)
importmap-rails (2.0.3)
actionpack (>= 6.0.0)
activesupport (>= 6.0.0)
railties (>= 6.0.0)
io-console (0.8.0)
irb (1.15.1)
pp (>= 0.6.0)
rdoc (>= 4.0.0)
reline (>= 0.4.2)
jmespath (1.6.2)
json (2.7.1)
jwt (2.7.1)
kgio (2.11.4)
language_server-protocol (3.17.0.3)
listen (3.8.0)
rb-fsevent (~> 0.10, >= 0.10.3)
rb-inotify (~> 0.9, >= 0.9.10)
loofah (2.22.0)
crass (~> 1.0.2)
nokogiri (>= 1.12.0)
mail (2.7.1)
mini_mime (>= 0.1.1)
marcel (1.0.2)
matrix (0.4.2)
method_source (1.0.0)
mini_mime (1.1.5)
mini_portile2 (2.8.7)
minitest (5.21.2)
minitest-ci (3.4.0)
minitest (>= 5.0.6)
msgpack (1.7.2)
multi_json (1.15.0)
multi_xml (0.6.0)
multipart-post (2.3.0)
mutex_m (0.2.0)
net-imap (0.4.9.1)
date
net-protocol
net-pop (0.1.2)
net-protocol
net-protocol (0.2.2)
timeout
net-sftp (4.0.0)
net-ssh (>= 5.0.0, < 8.0.0)
net-smtp (0.2.2)
digest
net-protocol
timeout
net-ssh (7.2.1)
nio4r (2.7.0)
nokogiri (1.16.7)
mini_portile2 (~> 2.8.2)
racc (~> 1.4)
nokogiri (1.16.7-aarch64-linux)
racc (~> 1.4)
nokogiri (1.16.7-arm-linux)
racc (~> 1.4)
nokogiri (1.16.7-arm64-darwin)
racc (~> 1.4)
nokogiri (1.16.7-x86-linux)
racc (~> 1.4)
nokogiri (1.16.7-x86_64-darwin)
racc (~> 1.4)
nokogiri (1.16.7-x86_64-linux)
racc (~> 1.4)
oauth2 (1.4.11)
faraday (>= 0.17.3, < 3.0)
jwt (>= 1.0, < 3.0)
multi_json (~> 1.3)
multi_xml (~> 0.5)
rack (>= 1.2, < 4)
parallel (1.24.0)
parser (3.3.1.0)
ast (~> 2.4.1)
racc
pdf-core (0.9.0)
pg (1.5.4)
posthog-ruby (2.5.0)
concurrent-ruby (~> 1)
pp (0.6.2)
prettyprint
prawn (2.4.0)
pdf-core (~> 0.9.0)
ttfunk (~> 1.7)
prettyprint (0.2.0)
pry (0.14.2)
coderay (~> 1.1)
method_source (~> 1.0)
pry-rails (0.3.9)
pry (>= 0.10.4)
psych (5.1.2)
stringio
puma (6.4.2)
nio4r (~> 2.0)
raabro (1.4.0)
racc (1.8.1)
rack (2.2.8)
rack-protection (3.2.0)
base64 (>= 0.1.0)
rack (~> 2.2, >= 2.2.4)
rack-test (2.1.0)
rack (>= 1.3)
rails (6.1.7.6)
actioncable (= 6.1.7.6)
actionmailbox (= 6.1.7.6)
actionmailer (= 6.1.7.6)
actionpack (= 6.1.7.6)
actiontext (= 6.1.7.6)
actionview (= 6.1.7.6)
activejob (= 6.1.7.6)
activemodel (= 6.1.7.6)
activerecord (= 6.1.7.6)
activestorage (= 6.1.7.6)
activesupport (= 6.1.7.6)
bundler (>= 1.15.0)
railties (= 6.1.7.6)
sprockets-rails (>= 2.0.0)
rails-dom-testing (2.2.0)
activesupport (>= 5.0.0)
minitest
nokogiri (>= 1.6)
rails-html-sanitizer (1.6.0)
loofah (~> 2.21)
nokogiri (~> 1.14)
railties (6.1.7.6)
actionpack (= 6.1.7.6)
activesupport (= 6.1.7.6)
method_source
rake (>= 12.2)
thor (~> 1.0)
rainbow (3.1.1)
raindrops (0.20.1)
rake (13.1.0)
rb-fsevent (0.11.2)
rb-inotify (0.10.1)
ffi (~> 1.0)
rdoc (6.12.0)
psych (>= 4.0.0)
record_tag_helper (1.0.1)
actionview (>= 5)
redis (4.5.1)
regexp_parser (2.9.2)
reline (0.6.0)
io-console (~> 0.5)
rexml (3.3.6)
strscan
rubocop (1.64.0)
json (~> 2.3)
language_server-protocol (>= 3.17.0)
parallel (~> 1.10)
parser (>= 3.3.0.2)
rainbow (>= 2.2.2, < 4.0)
regexp_parser (>= 1.8, < 3.0)
rexml (>= 3.2.5, < 4.0)
rubocop-ast (>= 1.31.1, < 2.0)
ruby-progressbar (~> 1.7)
unicode-display_width (>= 2.4.0, < 3.0)
rubocop-ast (1.31.3)
parser (>= 3.3.1.0)
rubocop-factory_bot (2.25.1)
rubocop (~> 1.41)
rubocop-rails (2.25.0)
activesupport (>= 4.2.0)
rack (>= 1.1)
rubocop (>= 1.33.0, < 2.0)
rubocop-ast (>= 1.31.1, < 2.0)
ruby-progressbar (1.13.0)
ruby-rc4 (0.1.5)
ruby-saml (1.17.0)
nokogiri (>= 1.13.10)
rexml
ruby2_keywords (0.0.5)
rufus-scheduler (3.9.1)
fugit (~> 1.1, >= 1.1.6)
sass-rails (6.0.0)
sassc-rails (~> 2.1, >= 2.1.1)
sassc (2.4.0)
ffi (~> 1.9)
sassc-rails (2.1.2)
railties (>= 4.0.0)
sassc (>= 2.0)
sprockets (> 3.0)
sprockets-rails
tilt
sentry-rails (5.17.3)
railties (>= 5.0)
sentry-ruby (~> 5.17.3)
sentry-ruby (5.17.3)
bigdecimal
concurrent-ruby (~> 1.0, >= 1.0.2)
sentry-sidekiq (5.17.3)
sentry-ruby (~> 5.17.3)
sidekiq (>= 3.0)
sidekiq (5.2.7)
connection_pool (~> 2.2, >= 2.2.2)
rack (>= 1.5.0)
rack-protection (>= 1.5.0)
redis (>= 3.3.5, < 5)
sidekiq-scheduler (3.0.1)
e2mmap
redis (>= 3, < 5)
rufus-scheduler (~> 3.2)
sidekiq (>= 3)
thwait
tilt (>= 1.4.0)
simplecov (0.22.0)
docile (~> 1.1)
simplecov-html (~> 0.11)
simplecov_json_formatter (~> 0.1)
simplecov-html (0.12.3)
simplecov_json_formatter (0.1.4)
sprockets (4.2.1)
concurrent-ruby (~> 1.0)
rack (>= 2.2.4, < 4)
sprockets-rails (3.4.2)
actionpack (>= 5.2)
activesupport (>= 5.2)
sprockets (>= 3.0.0)
stackprof (0.2.26)
stimulus-rails (1.3.4)
railties (>= 6.0.0)
stringio (3.1.5)
stripe (9.4.0)
strscan (3.1.0)
thor (1.3.0)
thwait (0.2.0)
e2mmap
tilt (2.3.0)
timeout (0.4.1)
ttfunk (1.7.0)
twilio-ruby (7.3.3)
faraday (>= 0.9, < 3.0)
jwt (>= 1.5, < 3.0)
nokogiri (>= 1.6, < 2.0)
typhoeus (1.4.1)
ethon (>= 0.9.0)
tzinfo (2.0.6)
concurrent-ruby (~> 1.0)
uglifier (4.2.0)
execjs (>= 0.3.0, < 3)
unicode-display_width (2.5.0)
unicorn (6.1.0)
kgio (~> 2.6)
raindrops (~> 0.7)
webrick (1.8.1)
websocket-driver (0.7.6)
websocket-extensions (>= 0.1.0)
websocket-extensions (0.1.5)
zeitwerk (2.6.12)
zip_tricks (5.6.0)
PLATFORMS
aarch64-linux
arm-linux
arm64-darwin
ruby
x86-linux
x86_64-darwin
x86_64-linux
DEPENDENCIES
awesome_print
aws-sdk-autoscaling
aws-sdk-core (~> 3.48)
aws-sdk-ec2
aws-sdk-rds
aws-sdk-s3
bcrypt
bigdecimal
bootsnap
bootstrap-sass (~> 3.4.1)
browser (~> 2.5.3)
coffee-rails
colored
combine_pdf (~> 1.0.23)
debug (>= 1.0.0)
dotenv-rails (~> 3.1.2)
drb
ethon
factory_bot
faraday (~> 1.0)
firefly_server
geocodio
http-cookie
importmap-rails (~> 2.0)
listen
mail (~> 2.7.1)
method_source
minitest-ci
mutex_m
net-imap
net-pop
net-sftp
net-smtp (~> 0.2.0)
net-ssh
oauth2 (~> 1.4.3)
pg
posthog-ruby
prawn (~> 2.4)
pry
pry-rails
psych (~> 5.1.0)
puma
rails (~> 6.1)
record_tag_helper (~> 1.0.1)
redis (< 4.6)
rexml
rubocop
rubocop-factory_bot
rubocop-rails
ruby-saml (~> 1.17.0)
sass-rails (>= 5)
sentry-rails
sentry-ruby
sentry-sidekiq
sidekiq (~> 5.2.7)
sidekiq-scheduler (~> 3.0.0)
simplecov
sprockets (~> 4)
sprockets-rails
stackprof
stimulus-rails (~> 1.3)
stripe (~> 9.4.0)
thwait
twilio-ruby (= 7.3.3)
typhoeus
uglifier
unicorn (~> 6.1)
webrick
zip_tricks
RUBY VERSION
ruby 3.3.0p0
BUNDLED WITH
2.5.4
Alrighty! Here's an even more minimal proof of concept, without Rails, ActiveSupport, etc.
Running it is trivial, and the instructions are in the readme.
I was able to upgrade Puma to 6.6.0 (latest) and still trigger the bug. I also tried out latest public stable ruby 3.4.1 and no change.
However switching to unicorn resolves the issue. I briefly tried thin but it failed to install on the first try and I didn't want to get distracted.
Hey I ran into this today. Thanks for the discussion above. If it helps I noticed that when running 1 worker the hanging issue where you cannot continue/quit no longer occurs, although the issue where you attach to the puma worker process when a debugger hasn't been hit still does
I found that adding Phlex to an absolute minimal rails codebase triggers this, breaking ruby/debug completely. Latest ruby, rails, ruby/debug, and puma. https://github.com/yippee-fun/phlex/issues/958
