Bug #17505: Can `Thread#group` actually be `nil`?

• Status: Closed
• Assignee: -
• Target version: -
• Backport: 2.5: UNKNOWN, 2.6: UNKNOWN, 2.7: UNKNOWN

[marcandre (Marc-Andre Lafortune)]

Is there a circumstance where Thread#group could actually be nil?

The documentation says so, there seems to be source code for this, but I can find no test or RubySpec for this and I don't see anywhere in the ThreadGroup API that could allow this.

[jeremyevans0 (Jeremy Evans)]

I've added a pull request that fixes the documentation and removes code that deals with a missing thread group: https://github.com/ruby/ruby/pull/4163

• Status changed from Open to Closed

Applied in changeset git|fc83b4896e9d7de084b203b133b84c1209c6ad88.

---

Don't document that Thread#group can return nil

Thread's are assigned a group at initialization, and no API exists
for them to unassign them from a group without assigning them to
another group.

Fixes [Bug #17505]

[znz (Kazuhiro NISHIYAMA)]

Just FYI

Japanese documents says

死んでいるスレッドは nil を返します。

Dead thread's group returns nil from 1.8.0 to 1.9.0-0.

% docker run -it --rm ghcr.io/ruby/all-ruby env ALL_RUBY_SINCE=ruby-1.8 ./all-ruby -e 'th=Thread.start{};Thread.pass;p th.group.class'
ruby-1.8.0            NilClass
...
ruby-1.9.0-0          NilClass
ruby-1.9.0-1          ThreadGroup
...
ruby-3.0.0            ThreadGroup

[marcandre (Marc-Andre Lafortune)]

Perfect, so this confirms the spec has changed a long time ago 👍