[ruby-dev:52070] [Ruby master Bug#20311] Struct.new("A") memory leak?

["byroot (Jean Boussier) via ruby-dev" <ruby-dev@ml.ruby-lang.org>]

Issue #20311 has been updated by byroot (Jean Boussier).


I had a quick look at this using `ObjectSpace.dump_all`, and it appears that these classes are being retained in the VM root:

```ruby
require 'objspace'

3.times do
  puts ObjectSpace.dump(Struct.new("A"))
  Struct.send(:remove_const, :A)
end

GC.start
ObjectSpace.dump_all(output: File.open("/tmp/heap.json", "w+"))
```

```
{"address":"0x102bc33f8", "type":"CLASS", ....
{"address":"0x102bc3218", "type":"CLASS", ....
{"address":"0x102bc3038", "type":"CLASS", ....
```

```
$ rg -F '"0x102bc3218"' /tmp/heap.json 
1:{"type":"ROOT", "root":"vm", "references":[..., "0x102bc3218"
$ rg -F '"0x102bc33f8"' /tmp/heap.json 
1:{"type":"ROOT", "root":"vm", "references":[..., "0x102bc33f8"
```



----------------------------------------
Bug #20311: Struct.new("A") memory leak?
https://bugs.ruby-lang.org/issues/20311#change-107049

* Author: MaxLap (Maxime Lapointe)
* Status: Open
* ruby -v: 3.3.0
* Backport: 3.0: UNKNOWN, 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN
----------------------------------------
The following code gives the impression of a memory leak.

```
10.times do
  5000.times do
    Struct.new("A")
    Struct.send(:remove_const, :A)
  end

  GC.start
  puts `ps -o rss= -p #{$$}`.to_i
end
```

```
27868
35324
43400
51472
58676
66144
73764
81196
88512
95752
```

Is there another location where the struct gets set that I need to clear up for the GC free the memory?

Happens in 3.2.2, 3.2.3, 3.3.0, 3.3-head, ruby-head.



-- 
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