[ruby-core:124351] [Ruby Bug#21802] segmentation fault when installing gems on CI

23 Dec 2025

      Issue #21802 has been reported by luizkowalski (Luiz Kowalski).

----------------------------------------
Bug #21802: segmentation fault when installing gems on CI
https://bugs.ruby-lang.org/issues/21802

* Author: luizkowalski (Luiz Kowalski)
* Status: Open
* ruby -v: ruby 3.4.8 (2025-12-17 revision 995b59f666) +YJIT +PRISM [aarch64-linux]
* Backport: 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN
----------------------------------------
hey!

recently, we updated to Bundler v4 (currently running v4.0.3) and Ruby 3.4.8. Since then, one of our CircleCI steps has been failing repeatedly, often without logs. Sometimes it does fail with a log

```
Installing faraday-typhoeus 1.1.0
Fetching http 5.3.1
/usr/*****/lib/ruby/site_ruby/3.4.0/rubygems/package.rb:369: [BUG] Segmentation fault at 0x00007f336df8c100
ruby 3.4.8 (2025-12-17 revision 995b59f666) +PRISM [x86_64-linux]

-- Control frame information -----------------------------------------------
c:0026 p:---- s:0142 e:000141 CFUNC  :each_value
c:0025 p:0078 s:0138 e:000137 METHOD /usr/*****/lib/ruby/site_ruby/3.4.0/rubygems/package.rb:369
c:0024 p:0030 s:0131 e:000130 METHOD /usr/*****/lib/ruby/site_ruby/3.4.0/rubygems/package.rb:678
c:0023 p:0005 s:0125 e:000124 BLOCK  /usr/*****/lib/ruby/site_ruby/3.4.0/rubygems/package.rb:697
c:0022 p:0053 s:0121 e:000120 METHOD /usr/*****/lib/ruby/site_ruby/3.4.0/rubygems/package/tar_reader.rb:67
c:0021 p:0005 s:0114 e:000113 METHOD /usr/*****/lib/ruby/site_ruby/3.4.0/rubygems/package.rb:696
c:0020 p:0011 s:0108 e:000107 BLOCK  /usr/*****/lib/ruby/site_ruby/3.4.0/rubygems/package.rb:626
c:0019 p:0020 s:0104 e:000103 METHOD /usr/*****/lib/ruby/site_ruby/3.4.0/rubygems/package/tar_reader.rb:25
c:0018 p:0007 s:0098 e:000097 BLOCK  /usr/*****/lib/ruby/site_ruby/3.4.0/rubygems/package.rb:623 [FINISH]
c:0017 p:---- s:0094 e:000093 CFUNC  :open
c:0016 p:0013 s:0088 e:000087 METHOD /usr/*****/lib/ruby/site_ruby/3.4.0/rubygems/package/file_source.rb:30
c:0015 p:0015 s:0083 e:000082 METHOD /usr/*****/lib/ruby/site_ruby/3.4.0/rubygems/package.rb:622
c:0014 p:0008 s:0078 e:000077 METHOD /usr/*****/lib/ruby/site_ruby/3.4.0/rubygems/package.rb:603
c:0013 p:0005 s:0074 e:000073 METHOD /usr/*****/lib/ruby/site_ruby/3.4.0/rubygems/installer.rb:254
c:0012 p:0020 s:0070 e:000069 METHOD /home/circleci/.rubygems/gems/bundler-4.0.2/lib/bundler/rubygems_gem_installer.rb:140
c:0011 p:0196 s:0066 e:000065 METHOD /home/circleci/.rubygems/gems/bundler-4.0.2/lib/bundler/source/rubygems.rb:195
c:0010 p:0025 s:0052 e:000051 METHOD /home/circleci/.rubygems/gems/bundler-4.0.2/lib/bundler/installer/gem_installer.rb:54
c:0009 p:0003 s:0048 e:000047 METHOD /home/circleci/.rubygems/gems/bundler-4.0.2/lib/bundler/installer/gem_installer.rb:17
c:0008 p:0037 s:0042 e:000041 METHOD /home/circleci/.rubygems/gems/bundler-4.0.2/lib/bundler/installer/parallel_installer.rb:133
c:0007 p:0007 s:0033 e:000032 BLOCK  /home/circleci/.rubygems/gems/bundler-4.0.2/lib/bundler/installer/parallel_installer.rb:124
c:0006 p:0009 s:0028 e:000027 METHOD /home/circleci/.rubygems/gems/bundler-4.0.2/lib/bundler/worker.rb:62
c:0005 p:0030 s:0021 e:000019 BLOCK  /home/circleci/.rubygems/gems/bundler-4.0.2/lib/bundler/worker.rb:57
c:0004 p:0017 s:0016 e:000015 METHOD <internal:kernel>:168
c:0003 p:0004 s:0011 e:000010 METHOD /home/circleci/.rubygems/gems/bundler-4.0.2/lib/bundler/worker.rb:54
c:0002 p:0005 s:0006 e:000005 BLOCK  /home/circleci/.rubygems/gems/bundler-4.0.2/lib/bundler/worker.rb:90 [FINISH]
c:0001 p:---- s:0003 e:000002 DUMMY  [FINISH]

-- Ruby level backtrace information ----------------------------------------
/home/circleci/.rubygems/gems/bundler-4.0.2/lib/bundler/worker.rb:90:in 'block (2 levels) in create_threads'
/home/circleci/.rubygems/gems/bundler-4.0.2/lib/bundler/worker.rb:54:in 'process_queue'
<internal:kernel>:168:in 'loop'
/home/circleci/.rubygems/gems/bundler-4.0.2/lib/bundler/worker.rb:57:in 'block in process_queue'
/home/circleci/.rubygems/gems/bundler-4.0.2/lib/bundler/worker.rb:62:in 'apply_func'
/home/circleci/.rubygems/gems/bundler-4.0.2/lib/bundler/installer/parallel_installer.rb:124:in 'block in worker_pool'
/home/circleci/.rubygems/gems/bundler-4.0.2/lib/bundler/installer/parallel_installer.rb:133:in 'do_install'
/home/circleci/.rubygems/gems/bundler-4.0.2/lib/bundler/installer/gem_installer.rb:17:in 'install_from_spec'
/home/circleci/.rubygems/gems/bundler-4.0.2/lib/bundler/installer/gem_installer.rb:54:in 'install'
/home/circleci/.rubygems/gems/bundler-4.0.2/lib/bundler/source/rubygems.rb:195:in 'install'
/home/circleci/.rubygems/gems/bundler-4.0.2/lib/bundler/rubygems_gem_installer.rb:140:in 'spec'
/usr/*****/lib/ruby/site_ruby/3.4.0/rubygems/installer.rb:254:in 'spec'
/usr/*****/lib/ruby/site_ruby/3.4.0/rubygems/package.rb:603:in 'spec'
/usr/*****/lib/ruby/site_ruby/3.4.0/rubygems/package.rb:622:in 'verify'
/usr/*****/lib/ruby/site_ruby/3.4.0/rubygems/package/file_source.rb:30:in 'with_read_io'
/usr/*****/lib/ruby/site_ruby/3.4.0/rubygems/package/file_source.rb:30:in 'open'
/usr/*****/lib/ruby/site_ruby/3.4.0/rubygems/package.rb:623:in 'block in verify'
/usr/*****/lib/ruby/site_ruby/3.4.0/rubygems/package/tar_reader.rb:25:in 'new'
/usr/*****/lib/ruby/site_ruby/3.4.0/rubygems/package.rb:626:in 'block (2 levels) in verify'
/usr/*****/lib/ruby/site_ruby/3.4.0/rubygems/package.rb:696:in 'verify_files'
/usr/*****/lib/ruby/site_ruby/3.4.0/rubygems/package/tar_reader.rb:67:in 'each'
/usr/*****/lib/ruby/site_ruby/3.4.0/rubygems/package.rb:697:in 'block in verify_files'
/usr/*****/lib/ruby/site_ruby/3.4.0/rubygems/package.rb:678:in 'verify_entry'
/usr/*****/lib/ruby/site_ruby/3.4.0/rubygems/package.rb:369:in 'digest'
/usr/*****/lib/ruby/site_ruby/3.4.0/rubygems/package.rb:369:in 'each_value'

-- Threading information ---------------------------------------------------
Total ractor count: 1
Ruby thread count for this ractor: 44

-- Machine register context ------------------------------------------------
 RIP: 0x00007f336df8bffe RBP: 0x00007f333dd38270 RSP: 0x00007f333dd38190
 RAX: 0x00007f336df8c100 RBX: 0x000055fb7a768350 RCX: 0x000055fb7956d330
 RDX: 0x0000000000000000 RDI: 0x00007f336e501740 RSI: 0x0000000000000000
  R8: 0x0000000000000003  R9: 0x000055fb7fd9ab78 R10: 0x0000000055550083
 R11: 0x000055fb7fe9a1c1 R12: 0x00007f328c55e568 R13: 0x00007f328c55e568
 R14: 0x000055fb7fe9a1a8 R15: 0x0000000000000000 EFL: 0x0000000000010202

-- C level backtrace information -------------------------------------------
/bin/bash: line 5:  1060 Killed                  bundle install
```

while trying to find the root cause, I noticed that **rolling back to Ruby 3.4.7 solves the issue** .

there's not a lot going on with the CI step, too:

```yaml
verify-contract:
  docker:
    - image: cimg/ruby:3.4.8-node
      environment:
        RAILS_ENV: test
        MYSQL_HOST: 127.0.0.1
        MYSQL_STATSDB_HOST: 127.0.0.1
        CONTRACT_URL: << pipeline.parameters.contract_url >>
        CONSUMER_NAME: << pipeline.parameters.consumer_name >>
        CONSUMER_VERSION: << pipeline.parameters.consumer_version >>
        PROVIDER_VERSION: << pipeline.parameters.provider_version >>
        PUBLISH_VERIFICATION_RESULTS: true
        DYNAMODB_AWS_REGION: us-east-1
        DYNAMODB_AWS_ACCESS_KEY_ID: local
        DYNAMODB_AWS_SECRET_ACCESS_KEY: local
        DYNAMODB_AWS_ENDPOINT: http://dynamodb:8000
    - image: cimg/mysql:8.0.42
      environment:
        MYSQL_ALLOW_EMPTY_PASSWORD: 1
    - image: cimg/redis:8.4.0
    - image: amazon/dynamodb-local:latest
      name: dynamodb
      command: ["-jar", "DynamoDBLocal.jar", "-sharedDb"]
  steps:
    - checkout
    - vault/get-secrets:
        template-preset: "ruby-gem-read"
    - run:
        name: Install bundler
        command: |
          gem install bundler
    - run:
        name: Ruby Environment Information
        command: |
          gem env
          bundle config
    - run:
        name: Install deps and verify contracts
        command: |
          if [ ! -z "${PROVIDER_VERSION}" ]; then
            git checkout ${PROVIDER_VERSION}
          fi
          bundle config https://rubygems.pkg.github.com/xxxxx "${RUBYGEMS_USER}:${RUBYGEMS_PASSWORD}"
          bundle install
          bundle clean --force
          bundle exec rake database:recreate_all
          if [[ -z "$CONTRACT_URL" ]]; then
            bundle exec rake pact:verify
          else
            bundle exec rake pact:verify:at[$CONTRACT_URL] || true
          fi
```

-- 
https://bugs.ruby-lang.org/