From: "byroot (Jean Boussier) via ruby-core" <ruby-core@...>
Date: 2026-06-24T22:47:08+00:00
Subject: [ruby-core:125834] [Ruby Feature#22128] C API: Expose RB_OBJ_SET_FROZEN_SHAREABLE

Issue #22128 has been updated by byroot (Jean Boussier).


> since RB_OBJ_SET_FROZEN_SHAREABLE is shallow and doesn't verify that referenced objects are shareable, this seems very hard to use safely. 

I understand your reservation, I kinda have the same, but I think this being a C-level API is OK to be a sharp knife. There is a million other way you can crash the VM from a C extension, not even involving Ruby APIs.

In addition, it does check that the invariant is respected when running against `-DRUBY_DEBUG=1`, which I know not a lot of gems do, but isn't that hard to put in place with GHA `setup-ruby`.

Also on the very hard ot use safely part, I think this is a good fit for database clients, parsers etc. Could very well see `JSON.parse(..., shareable: true)`.

In these situation you are mostly dealing with Ruby primitives (String, Array, Hash) that you've just recursively built yourself, so it's easy to know there's no unaccounted references.

But you're right that with things like `Time`, `Date` etc, they're fine today, as they have no reference, but it could no longer be true at some point.

----------------------------------------
Feature #22128: C API: Expose RB_OBJ_SET_FROZEN_SHAREABLE
https://bugs.ruby-lang.org/issues/22128#change-117754

* Author: byroot (Jean Boussier)
* Status: Open
----------------------------------------
### Context

I'm trying to experiment with adapting Active Record for a Ractor architecture.

Since database connections can't possibly be Ractor shareable, the idea is to warp each connection inside its own ractor, and then send SQL queries and responses through a port.

But for this to perform well, I'd like to directly build the query response as a fully shareable object, so that it can be pushed into the port for free, instead of having Ruby need to recursively walk the potentially large response to mark objects as shareable.

Here's an example of how it would work in trilogy: https://github.com/trilogy-libraries/trilogy/pull/299

### Problem

Unfortunately, the necessary API isn't currently exposed in the C API:

  - `RB_OBJ_SET_FROZEN_SHAREABLE`
  - `RB_OBJ_SET_SHAREABLE` / `rb_obj_set_shareable`

I understand that this API could potentially be misused, but given it's a C API, I believe it's acceptable to require care from the caller.

### Benchmark

```ruby
# frozen_string_literal: true

require 'trilogy'
require 'benchmark/ips'

baseline = Trilogy.new(database: "test")
shareable = Trilogy.new(database: "test", shareable: true)


values = {
  null_test: "test",
  bit_test: "test",
  single_bit_test: 1,
  tiny_int_test: 2,
  bool_cast_test: true,
  small_int_test: 4,
  medium_int_test: 23434,
  int_test: 324234,
  big_int_test: 234234,
  unsigned_big_int_test: 23423423,
  float_test: 234234,
  float_zero_test: 213.23,
  double_test: 23123.12323,
  decimal_test: 123213.12312,
  decimal_zero_test: 213213.21323,
  date_test: "2026-01-30",
  date_time_test: "2026-01-30 14:03:56",
  date_time_with_precision_test: "2026-01-30 14:03:56.12",
  time_with_precision_test: "2026-01-30 14:03:56.12",
  timestamp_test: "2026-01-30 14:03:56.12",
  varchar_test: "VARCHAR"
}

baseline.query("DELETE FROM trilogy_test")
insert = "INSERT INTO trilogy_test(#{values.keys.join(", ")}) VALUES (#{values.values.map(&:inspect).join(", ")})"
1000.times do
  baseline.query(insert)
end

p shareable.query("SELECT * FROM test.trilogy_test").to_a.size
Benchmark.ips do |x|
  x.report("baseline") { Ractor.make_shareable(baseline.query("SELECT * FROM trilogy_test")) }
  x.report("shareable") { Ractor.make_shareable(shareable.query("SELECT * FROM trilogy_test")) }
  x.compare!(order: :baseline)
end
```

```
ruby 4.1.0dev (2026-06-24T13:17:28Z expose-ractor-set-.. f9d7dd50cd) +PRISM [arm64-darwin25]
Warming up --------------------------------------
            baseline    42.000 i/100ms
           shareable    66.000 i/100ms
Calculating -------------------------------------
            baseline    220.024 (�43.2%) i/s    (4.54 ms/i) -      1.134k in   5.153976s
           shareable    677.487 (� 2.4%) i/s    (1.48 ms/i) -      3.432k in   5.065782s

Comparison:
 baseline:      220.0 i/s
shareable:      677.5 i/s - 3.08x  faster
```



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