[NO-TICKET] Optimize CodeProvenance#record_loaded_files to avoid allocations

[ivoanjo]

What does this PR do?

This PR replaces a Hash#find with a Hash#any? in the Profiler CodeProvenance collector.

This seemingly innocuous change actually gets rid of a bunch of memory allocations.

It turns out that when Hash#find is being used, Ruby allocates an array to contain the [key, value] pair that's passed into the block, for each entry in the hash (on top of a few more objects -- but this is the biggest offender unless the hash is empty/almost empty).

The VM actually has an optimization for a lot of operations, including Hash#any? that avoids allocating any extra memory, but because Hash#find is actually inherited from Enumerable, this optimization does not kick in.

Motivation:

Eliminate unneeded memory allocations.

Additional Notes:

Here's a very simple reproducer that shows the issue:

puts RUBY_DESCRIPTION

def allocated_now; GC.stat(:total_allocated_objects); end

hash = {a: 1, b: 2, c: 3}
v = nil

before_find = allocated_now
10.times { _, v = hash.find { |k, _| k == :c } }
puts "Found value #{v}, allocated #{allocated_now - before_find}"

before_any = allocated_now
10.times { v = nil; hash.any? { |k, val| (v = val) if k == :c } }

puts "Found value #{v}, allocated #{allocated_now - before_any}"

and here's how it looks on the latest Ruby version:

ruby 3.4.0preview1 (2024-05-16 master 9d69619623) [x86_64-linux]
Found value 3, allocated 64
Found value 3, allocated 1

(Note that there's a few more allocations going on with Hash#find, not only the arrays for the pairs, and we get rid of them ALL!)

Here's a quick comparison of the internal prof-fibonacci test service with/without this change (+ sampling every allocation):

Before

After

How to test the change?

This operation already has test coverage. I considered adding some counting of allocated objects, but we've had quite a bunch of flakiness in some of the profiler specs when counting objects, so I've decided to not add any performance-specific tests for this.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 97.91%. Comparing base (849c60c) to head (f0be554).

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #3757   +/-   ##
=======================================
  Coverage   97.91%   97.91%           
=======================================
  Files        1241     1241           
  Lines       74632    74632           
  Branches     3605     3605           
=======================================
  Hits        73074    73074           
  Misses       1558     1558           

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[ivoanjo]

I've reported this upstream to https://bugs.ruby-lang.org/issues/20608 and there's ruby/ruby#11110 to improve this :)