From: marcandre-ruby-core@...
Date: 2021-07-09T06:34:58+00:00
Subject: [ruby-core:104555] [Ruby master Bug#18032] Openstruct is ~20..25x slower with Ruby 3.0.0 and 3.0.1 compared to earlier versions

Issue #18032 has been updated by marcandre (Marc-Andre Lafortune).

Status changed from Assigned to Rejected

@mame is correct that #15409 was a concern, but this is mainly due to #12136 and listed in the release notes for 3.0.

Basically we have prioritized correctness over performance and came back to a solution similar to that of Ruby 2.2.

Note that only initialization from a Hash was impacted, but setting the attributes one by one was not much impacted.

If the benchmarking code is changed:

```ruby
# before
OpenStruct.new(:name => "User", :age => 21)
# after
o = OpenStruct.new
o.name = "User"
o.age = 21
```

You'll see that this similar code was always slow.

The documentation now states the multiple caveats of OpenStruct, one of which is performance.

A different class that would not define methods but use only `method_missing` would be faster, but not quite as accurate.

----------------------------------------
Bug #18032: Openstruct is ~20..25x slower with Ruby 3.0.0 and 3.0.1 compared to earlier versions
https://bugs.ruby-lang.org/issues/18032#change-92834

* Author: TiloS (Tilo S)
* Status: Rejected
* Priority: Normal
* Assignee: marcandre (Marc-Andre Lafortune)
* ruby -v: 3.0.0
* Backport: 2.6: UNKNOWN, 2.7: UNKNOWN, 3.0: UNKNOWN
----------------------------------------
Doing some timings with different Ruby versions, I noticed that when using Ruby 3.0.0 and 3.0.1 
the time to create OpenStruct instances has significantly increased by 20..25x

```

0.936016 seconds elapsed for Class.new (Ruby 2.7.2)
0.453067 seconds elapsed for Struct (Ruby 2.7.2)
1.016676 seconds elapsed for Hash (Ruby 2.7.2)
1.482318 seconds elapsed for OpenStruct (Ruby 2.7.2)

0.421272 seconds elapsed for Class.new (Ruby 3.0.0)
0.322617 seconds elapsed for Struct (Ruby 3.0.0)
0.719928 seconds elapsed for Hash (Ruby 3.0.0)
35.130777 seconds elapsed for OpenStruct (Ruby 3.0.0) (oops!)
```

see also: https://stackoverflow.com/questions/1177594/when-should-i-use-struct-vs-openstruct/5440064#5440064

Can someone please look into this? 

---Files--------------------------------
OpenStruct_timing.rb (1.04 KB)


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