[ruby-core:112347] [Ruby master Bug#19424] Significant performance decreases in `OpenStruct#marshal_load` in Ruby 3.0 and 3.1

Issue #19424 has been updated by jeremyevans0 (Jeremy Evans).


jeremyevans0 (Jeremy Evans) wrote in #note-4:
> So part of the issue is `ostruct` (due to the commit mentioned), and part of the issue appears to be `Marshal.load` changes in 3.0.

Well, not `Marshal.load`, but the initialization approach `ostruct` switched to became slower in Ruby 3.0.  New benchmark:

```ruby
require 'benchmark'
gem 'ostruct'
require 'ostruct'
p ["OpenStruct::VERSION", OpenStruct::VERSION]

n = 100_000
obj = OpenStruct.new( one: nil )

Benchmark.bm(20) do |x|
  klass = obj.class
  x.report("#{klass} dump") do
    n.times do
      Marshal.dump(obj)
    end
  end

  m = Marshal.dump(obj)
  x.report("#{klass} load") do
    n.times do
      Marshal.load(m)
    end
  end

  x.report("#{klass} new") do
    n.times do
      OpenStruct.new( one: nil )
    end
  end
end
```

output:

```
ruby 2.7.7p221 (2022-11-24 revision 168ec2b1e5) [x86_64-openbsd]
["OpenStruct::VERSION", "0.5.5"]
                           user     system      total        real
OpenStruct dump        0.510000   0.010000   0.520000 (  0.518952)
OpenStruct load        1.390000   0.000000   1.390000 (  1.389447)
OpenStruct new         1.000000   0.000000   1.000000 (  1.016224)
ruby 3.0.5p211 (2022-11-24 revision ba5cf0f7c5) [x86_64-openbsd]
["OpenStruct::VERSION", "0.5.5"]
                           user     system      total        real
OpenStruct dump        0.520000   0.000000   0.520000 (  0.537284)
OpenStruct load        2.190000   0.000000   2.190000 (  2.191907)
OpenStruct new         1.680000   0.000000   1.680000 (  1.679188)
ruby 3.1.3p185 (2022-11-24 revision 1a6b16756e) [x86_64-openbsd]
["OpenStruct::VERSION", "0.5.5"]
                           user     system      total        real
OpenStruct dump        0.580000   0.000000   0.580000 (  0.562538)
OpenStruct load        2.210000   0.000000   2.210000 (  2.242819)
OpenStruct new         1.650000   0.000000   1.650000 (  1.672738)
```

----------------------------------------
Bug #19424: Significant performance decreases in `OpenStruct#marshal_load` in Ruby 3.0 and 3.1
https://bugs.ruby-lang.org/issues/19424#change-101791

* Author: sumitdey035 (Sumit Dey)
* Status: Open
* Priority: Normal
* ruby -v: 3.1.2
* Backport: 2.7: UNKNOWN, 3.0: UNKNOWN, 3.1: UNKNOWN, 3.2: UNKNOWN
----------------------------------------
I can see degradation in **Marshal load** only in Ruby 3.1.2 compared to 2.7.4
Processing time increased by 200%(2.4 sec to 4.3 sec)
Memory allocation increased by 600%(6500001 to 39000004)

```
require 'benchmark'
require 'ostruct'

N_OJ = 500_000

ex_HASH = { 'one' => 1, 'array' => [ true, false ] }
ex_JSON = '{ "one": 1, "array": [ true, false ] }'

ex_STRUCT = OpenStruct.new( one: 1, hash: ex_HASH, array: [ true, false ] )
ex_MARSHAL = "\x04\bU:\x0FOpenStruct{\b:\bonei\x06:\thash{\aI\"\bone\x06:\x06ETi\x06I\"\narray\x06;\bT[\aTF:\narray[\aTF"

"-----------------Ruby #{system("rbenv version")}----------------"

Benchmark.bm(20) do |x|
  x.report('native marshal dump') do
    N_OJ.times do
      y = Marshal.dump(ex_STRUCT)
    end
  end

  x.report('native marshal load') do
    N_OJ.times do
      y = Marshal.load(ex_MARSHAL)
    end
  end

  start_memory = GC.stat[:total_allocated_objects]
  N_OJ.times do
    y = Marshal.dump(ex_STRUCT)
  end
  end_memory = GC.stat[:total_allocated_objects]
  print "Marshal dump memory allocation- #{end_memory - start_memory}\n"

  start_memory = GC.stat[:total_allocated_objects]
  N_OJ.times do
    y = Marshal.load(ex_MARSHAL)
  end
  end_memory = GC.stat[:total_allocated_objects]
  print "Marshal load memory allocation- #{end_memory - start_memory}\n"
end```

**Benchmark and Memory consumption result**
![](Screenshot 2023-02-07 at 1.04.49 PM.png)


---Files--------------------------------
Screenshot 2023-02-07 at 1.04.49 PM.png (184 KB)


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