[ruby-core:112338] [Ruby master Bug#19424] Significant performance decreases in `OpenStruct#marshal_load` in Ruby 3.0 and 3.1

10 Feb 2023

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

Subject changed from Degradation in **Marshal load** only in Ruby 3.1.2 compared to 2.7.4 to Significant performance decreases in `OpenStruct#marshal_load` in Ruby 3.0 and 3.1

I was able to reproduce the issue.  It seems to be limited to OpenStruct.  Here's a simpler example:

```ruby
require 'benchmark'
require 'ostruct'

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
end

```

with results:

```
$ ruby27 -v t.rb && ruby30 -v t.rb && ruby31 -v t.rb
ruby 2.7.7p221 (2022-11-24 revision 168ec2b1e5) [x86_64-openbsd]
                           user     system      total        real
OpenStruct dump        0.520000   0.000000   0.520000 (  0.523775)
OpenStruct load        0.370000   0.000000   0.370000 (  0.376001)
ruby 3.0.5p211 (2022-11-24 revision ba5cf0f7c5) [x86_64-openbsd]
                           user     system      total        real
OpenStruct dump        0.540000   0.000000   0.540000 (  0.537673)
OpenStruct load        1.590000   0.000000   1.590000 (  1.595759)
ruby 3.1.3p185 (2022-11-24 revision 1a6b16756e) [x86_64-openbsd]
                           user     system      total        real
OpenStruct dump        0.550000   0.000000   0.550000 (  0.556089)
OpenStruct load        2.240000   0.000000   2.240000 (  2.243714)
```

Ruby 3.2 performance is about the same as Ruby 3.1.

----------------------------------------
Bug #19424: Significant performance decreases in `OpenStruct#marshal_load` in Ruby 3.0 and 3.1
https://bugs.ruby-lang.org/issues/19424#change-101781

* 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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