[ruby-core:99570] [Ruby master Feature#17103] Add a :since option to ObjectSpace.dump_all

Issue #17103 has been updated by byroot (Jean Boussier).


@ko1 this parameter allow to do partial heap dumps. e.g. `dump_all(since: 42)`, means to only dump objects of the 42th generation and later. Basically like adding a `if ObjectSpace.allocation_generation(obj) >= 42`.

This would be very useful to me, because a minimal heap dump of our application is over 1GiB and take almost a minute to be performed. Often times I'm only interested by allocations past a certain point, such filtering criterias would allow for much smaller and faster dumps, with less "noise" in them.

Please let me know if that is still unclear.

> also https://github.com/ruby/ruby/pull/3368/files doesn't have a doc.

That's an oversight on my part, I'll update the PR to add a documentation for that new parameter as soon as possible.

----------------------------------------
Feature #17103: Add a :since option to ObjectSpace.dump_all
https://bugs.ruby-lang.org/issues/17103#change-87037

* Author: byroot (Jean Boussier)
* Status: Open
* Priority: Normal
----------------------------------------
Patch: https://github.com/ruby/ruby/pull/3368

This is useful for seeing what a block of code allocated, e.g.

```ruby
GC.start
GC.disable
gc_gen = GC.count
ObjectSpace.trace_object_allocations do
  # run some code
end
allocations = ObjectSpace.dump_all(output: :file, since: gc_gen)
GC.enable
GC.start
retentions = ObjectSpace.dump_all(output: :file, since: gc_gen)
```

For context, this is what I do in https://github.com/Shopify/heap-profiler, except that I have to dump the entire heap three times and then do a diff. This new API would allow me to dump the entire heap only once and then do two much-faster single-generation dumps without doing the diff.



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