[ruby-core:115954] [Ruby master Feature#19333] Setting (Fiber Local|Thread Local|Fiber Storage) to nil should delete value in order to avoid memory leaks.

Issue #19333 has been updated by ioquatix (Samuel Williams).


This is implemented for `Fiber#storage` in Ruby 3.3.

I'll consider expanding it to Thread and Fiber locals as it was agreed on but has a bigger blast radius.

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Feature #19333: Setting (Fiber Local|Thread Local|Fiber Storage) to nil should delete value in order to avoid memory leaks.
https://bugs.ruby-lang.org/issues/19333#change-105911

* Author: ioquatix (Samuel Williams)
* Status: Open
* Priority: Normal
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As it stands, Fiber Locals, Thread Locals and Fiber Storage have no way of deleting key-value associations.

```ruby
100.times do |i|
  name = :"variable-#{i}"
  Thread.current[name] = 10
end
```

Because of this, dynamically generated associations can leak over time. This is worse for things like Threads that might be pooled (or maybe an argument against user-space pooling).

In any case, having a way to delete those associations would allow application code to at least delete the associations when they no longer make sense.

I propose that assigning `nil` to "locals" or "storage" should effectively delete them.

e.g.

```ruby
100.times do |i|
  name = :"variable-#{i}"
  Thread.current[name] = 10
  Thread.current[name] = nil # delete association
end
```

A more invasive alternative would be to define new interfaces like `Thread::Local`, `Fiber::Local` and `Fiber::Storage::Local` (or something) which correctly clean up on GC.



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