ruby-concurrency/concurrent-ruby

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Modern concurrency tools including agents, futures, promises, thread pools, supervisors, and more. Inspired by Erlang, Clojure, Scala, Go, Java, JavaScript, and classic concurrency patterns.

Stars: 5.8k
Forks: 420
Open beginner issues: 0
Indexed issues: 49
Avg merge: 20h 45m
Merged PRs (30d): 4

Dominant language: Ruby
License: No license data
Last GitHub push: Aug 31, 2026
Latest indexed: Sep 20, 2026
Contributing guide: Contributing guide
Code of conduct: Code of conduct
Beginner labels: No beginner labels indexed

Beginner friendly Everything

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49 open issues indexed

Proposal: Explore a CAS fast path for Semaphore with native atomics Open

Difficulty 5/5 Over a week Newbie friendliness 35/100

ruby-concurrency/concurrent-ruby#1118 · Opened Sep 13, 2026
Deadlock race when calling ScheduledTask#reschedule Open

Difficulty 4/5 3-5 days Newbie friendliness 35/100

ruby-concurrency/concurrent-ruby#1099 · 9 comments · Opened Feb 3, 2026
Implement FIFO and LRU caches through a Map memory limit Open

Difficulty 5/5 Over a week Newbie friendliness 25/100

ruby-concurrency/concurrent-ruby#1095 · 8 comments · Opened Dec 8, 2025
concurrent-ruby rspec testsuite fails with ruby4.0.0dev perhaps due to Set change Open

Difficulty 4/5 3-5 days Newbie friendliness 35/100

ruby-concurrency/concurrent-ruby#1093 · 3 comments · Opened Nov 16, 2025
concurrent_ruby.jar included in gem has no version information included Open

Difficulty 2/5 1-3 hours Newbie friendliness 45/100

ruby-concurrency/concurrent-ruby#1091 · Opened Sep 4, 2025
ThreadPoolExecutor#kill: documentation and implementation are out of sync Open

Difficulty 3/5 1-2 days Newbie friendliness 35/100

ruby-concurrency/concurrent-ruby#1072 · 1 reaction · Opened Nov 26, 2024
Review usages of Integer#size in the gem Open

Difficulty 4/5 3-5 days Newbie friendliness 40/100

ruby-concurrency/concurrent-ruby#1057 · 4 comments · 1 reaction · Opened Jul 25, 2024
should the thread_local_var_accessor gem be included within the concurrent-ruby gem? Open

Difficulty 5/5 Over a week Newbie friendliness 25/100

ruby-concurrency/concurrent-ruby#1056 · 4 comments · Opened Jul 25, 2024
Add keyword arguments to async Open

Difficulty 3/5 1-2 days Newbie friendliness 35/100

ruby-concurrency/concurrent-ruby#1040 · 5 comments · Opened Feb 11, 2024
Add API to prestart threads in threadpools Open

Difficulty 4/5 3-5 days Newbie friendliness 35/100

ruby-concurrency/concurrent-ruby#1032 · 5 comments · Opened Jan 17, 2024
[REDIRECT] Segfault on Ruby 3.3.0 on linux-aarch64? See https://bugs.ruby-lang.org/issues/20085 Open

Difficulty 1/5 Under an hour Newbie friendliness 10/100

ruby-concurrency/concurrent-ruby#1023 · 27 reactions · Opened Dec 27, 2023
DaemonThreadFactory creating new Java thread factory each time it creates a new thread Open

Difficulty 2/5 1-3 hours Newbie friendliness 45/100

ruby-concurrency/concurrent-ruby#1008 · 8 comments · Opened Aug 24, 2023
why use wait_for_termination method will stuck the code Open

Difficulty 4/5 3-5 days Newbie friendliness 30/100

ruby-concurrency/concurrent-ruby#1004 · 2 comments · Opened Jul 14, 2023
CAtomicFixnum should probably be a private constant Open

Difficulty 4/5 3-5 days Newbie friendliness 25/100

ruby-concurrency/concurrent-ruby#981 · 1 comment · Opened Jan 8, 2023
`Concurrent::Hash` default initialization is not fully thread-safe Open

high-priority

ruby-concurrency/concurrent-ruby#970 · 8 comments · 3 reactions · 1 assignee · Opened Nov 17, 2022
Memory leak in Concurrent::Promises.future Open

Difficulty 4/5 3-5 days Newbie friendliness 38/100

ruby-concurrency/concurrent-ruby#960 · 1 comment · Opened Aug 4, 2022
Memory leak in Concurrent::Future Open

Difficulty 4/5 3-5 days Newbie friendliness 35/100

ruby-concurrency/concurrent-ruby#959 · 2 comments · Opened Aug 4, 2022
Concurrent::Hash and Concurrent::Array are not fully threadsafe on CRuby Open

high-priority

ruby-concurrency/concurrent-ruby#929 · 9 comments · 1 reaction · 1 assignee · Opened Dec 14, 2021
should we use new c macros included with rubyc? Open

enhancement looking-for-contributor

Difficulty 5/5 Over a week Newbie friendliness 20/100

ruby-concurrency/concurrent-ruby#897 · 1 comment · Opened Jan 5, 2021
Use channel as a stremming object Open

Difficulty 5/5 Over a week Newbie friendliness 25/100

ruby-concurrency/concurrent-ruby#895 · Opened Nov 13, 2020
concurrent-ruby-edge Channel.select consumes full(single core) cpu Open

Difficulty 3/5 1-2 days Newbie friendliness 35/100

ruby-concurrency/concurrent-ruby#883 · 1 comment · Opened Aug 28, 2020
Passenger workers hang / segfault with Ruby 2.5 / concurrent-ruby 1.1.6 Open

bug

Difficulty 4/5 3-5 days Newbie friendliness 25/100

ruby-concurrency/concurrent-ruby#871 · 3 comments · Opened May 15, 2020
Promise.zip hangs on rejected promise in chain Open

Difficulty 4/5 3-5 days Newbie friendliness 35/100

ruby-concurrency/concurrent-ruby#870 · Opened May 8, 2020
Bad test behavior when transient test threads die Open

Difficulty 3/5 1-2 days Newbie friendliness 52/100

ruby-concurrency/concurrent-ruby#862 · Opened Apr 8, 2020
Concurrent::Promises::Channel deadlock in example code Open

Difficulty 4/5 3-5 days Newbie friendliness 35/100

ruby-concurrency/concurrent-ruby#860 · 1 comment · 2 reactions · Opened Mar 19, 2020
New lighter task scheduler for promises Open

enhancement

Difficulty 5/5 Over a week Newbie friendliness 30/100

ruby-concurrency/concurrent-ruby#827 · Opened Oct 6, 2019
Waiting for Actor termination? Open

question

Difficulty 4/5 3-5 days Newbie friendliness 35/100

ruby-concurrency/concurrent-ruby#825 · 1 comment · Opened Sep 18, 2019
LazyRegister concurrent register bug Open

enhancement

ruby-concurrency/concurrent-ruby#819 · 3 comments · 1 assignee · Opened Aug 24, 2019
Actor pool terminated event sent as message Open

question

ruby-concurrency/concurrent-ruby#813 · 1 assignee · Opened Jun 22, 2019
Backtrace propagation into the executor Open

enhancement looking-for-contributor

Difficulty 4/5 3-5 days Newbie friendliness 35/100

ruby-concurrency/concurrent-ruby#810 · 6 comments · Opened May 25, 2019
Promoting the Actor implmentation from edge to proper concurrent-ruby? Open

chore enhancement

Difficulty 5/5 Over a week Newbie friendliness 25/100

ruby-concurrency/concurrent-ruby#809 · 2 comments · 3 reactions · Opened May 20, 2019
Support Hash of Futures for Promises.zip Open

enhancement looking-for-contributor

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

ruby-concurrency/concurrent-ruby#777 · 7 comments · 4 reactions · Opened Nov 7, 2018
Java and Ruby thread do enqueue/create-threads differently Open

bug

ruby-concurrency/concurrent-ruby#726 · 1 comment · 1 assignee · Opened May 30, 2018
Deadlock on wait_for_termination Open

pending question

Difficulty 4/5 3-5 days Newbie friendliness 25/100

ruby-concurrency/concurrent-ruby#703 · 2 comments · Opened Apr 5, 2018
Keyword parameters for MutableStruct in Ruby 2.5.0 Open

enhancement medium-priority

ruby-concurrency/concurrent-ruby#694 · 3 comments · 1 assignee · Opened Jan 26, 2018
Thread pools behaving oddly with `max_queue` and `remaining_capacity` Open

question

Difficulty 4/5 3-5 days Newbie friendliness 35/100

ruby-concurrency/concurrent-ruby#684 · 6 comments · Opened Dec 6, 2017
Thread pool exception handling Open

bug medium-priority

ruby-concurrency/concurrent-ruby#634 · 16 comments · 8 reactions · 1 assignee · Opened Mar 2, 2017
Deadlock in Concurrent::Array's on non-MRI Open

bug looking-for-contributor medium-priority

Difficulty 5/5 Over a week Newbie friendliness 25/100

ruby-concurrency/concurrent-ruby#627 · 4 comments · Opened Feb 2, 2017
Allow concurrent iteration and writes in Concurrent::Hash Open

bug looking-for-contributor medium-priority

Difficulty 5/5 Over a week Newbie friendliness 15/100

ruby-concurrency/concurrent-ruby#599 · 1 comment · Opened Nov 6, 2016
Remove all global state not just configuration Open

enhancement

ruby-concurrency/concurrent-ruby#595 · 11 comments · 1 assignee · Opened Nov 5, 2016
Rails5, auto-loading, future, circular dependency Open

enhancement medium-priority

ruby-concurrency/concurrent-ruby#585 · 49 comments · 7 reactions · 1 assignee · Opened Oct 13, 2016
AtomicBoolean: add compare_and_set API Open

enhancement looking-for-contributor medium-priority

Difficulty 3/5 1-2 days Newbie friendliness 35/100

ruby-concurrency/concurrent-ruby#540 · 7 comments · Opened Jun 24, 2016
Exception catching Open

enhancement medium-priority

ruby-concurrency/concurrent-ruby#511 · 3 comments · 1 assignee · Opened Feb 15, 2016
CSP channels implementation Open

enhancement

ruby-concurrency/concurrent-ruby#510 · 4 comments · 1 assignee · Opened Feb 14, 2016
Add bounded message box for actors Open

enhancement

Difficulty 5/5 Over a week Newbie friendliness 20/100

ruby-concurrency/concurrent-ruby#495 · 2 comments · Opened Jan 14, 2016
No good tools for long streams of tasks Open

enhancement looking-for-contributor medium-priority

Difficulty 5/5 Over a week Newbie friendliness 25/100

ruby-concurrency/concurrent-ruby#493 · 15 comments · 3 reactions · Opened Jan 9, 2016
Drop Delay from global config Open

enhancement looking-for-contributor

ruby-concurrency/concurrent-ruby#460 · 8 comments · 1 assignee · Opened Nov 2, 2015
Migrate all abstractions to Synchronisation layer or to edge Open

bug

ruby-concurrency/concurrent-ruby#459 · 1 comment · 1 assignee · Opened Nov 2, 2015
Copy select thread local state of calling thread into workers Open

enhancement medium-priority

ruby-concurrency/concurrent-ruby#456 · 8 comments · 1 assignee · Opened Oct 29, 2015

ruby-concurrency/concurrent-ruby

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