[PROF-7307] Record allocation type when sampling objects #3096
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**What does this PR do?** This PR extends the `Profiling::Collectors::ThreadContext` support for sampling allocated objects to also record the object's class. **Motivation:** This will enable us to provide the "Allocations by Allocated Type" feature in the Datadog UX. **Additional Notes:** N/A **How to test the change?** This change includes test coverage. Right now, there's no way to exercise this code other than through tests, because we haven't yet wired it up to trigger during actual Ruby VM allocations. This will come at a later date.
I suspect the allocation types may get a bit expensive on legacy Rubies, and plan to experiment more about this at some point. For now, to enable quick experiments, I've decided to add a flag to make it easy to toggle this behavior. I haven't decided if we'll ever expose this flag to customers or not. If you're reading this in a few months' time, and this disabling feature was never used, go ahead and delete it.
Hopefully we'll be able to deprecate Ruby 2.3 soon...
I guess we'd need to use pattern matching on Ruby 3 to do something similar as Ruby 2 code, but we can't make that work on all Rubies we support, so let's just do it the manual way.
After thinking about it for a bit longer, let's just treat immediates the same way as every other type in the allocations code. They are never allocated, but the extra codepaths/complexity to treat them separately seems more brittle than just treating them as any other type.
marcotc
approved these changes
Aug 31, 2023
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What does this PR do?
This PR extends the
Profiling::Collectors::ThreadContextsupport for sampling allocated objects to also record the object's class.Motivation:
This will enable us to provide the "Allocations by Allocated Type" feature in the Datadog UX.
Additional Notes:
N/A
How to test the change?
This change includes test coverage. Right now, there's no way to exercise this code other than through tests, because we haven't yet wired it up to trigger during actual Ruby VM allocations. This will come at a later date.
For Datadog employees:
credentials of any kind, I've requested a review from
@DataDog/security-design-and-guidance.