Cache importlib_metadata.entry_points

[alexmojaki]

Description

Fixes #3054

Changes opentelemetry.util._importlib_metadata.entry_points to a version with some caching instead of just an alias of the original importlib_metadata.entry_points.

Type of change

Performance improvement, shouldn't break anything, unless it's possible for the result of the original importlib_metadata.entry_points() to change midway through a program run in a way that affects OTel, i.e. if some OTel entry point is registered at runtime.

How Has This Been Tested?

Run this script with and without this PR:

import time

start_time = time.perf_counter()

from opentelemetry import context, propagate
from opentelemetry.sdk.resources import Resource

# mark imports as used for formatter
str(context)
str(propagate)

Resource.create()

end_time = time.perf_counter()
print(end_time - start_time)

I personally see a ~10% performance improvement in this repo, but I know it can be significantly more in environments with many packages installed.

Does This PR Require a Contrib Repo Change?

No.

Checklist:

• Followed the style guidelines of this project
• Changelogs have been updated
• Unit tests have been added existing tests should suffice, they use the new code implicitly
• Documentation has been updated I don't think this needs docs, but there's a docstring

[emdneto]

Looks good.
Created a simple benchmark test and got an Overall speedup of 6.43x

opentelemetry-sdk/benchmarks/test_entrypoints.py

def test_resource_entry_points(benchmark):
    def create_some_resources():
        from opentelemetry import context, propagate
        from opentelemetry.sdk.resources import Resource

        str(context)
        str(propagate)

        Resource.create()

    benchmark(create_some_resources)

tox -e benchmark-opentelemetry-sdk -- -k 'test_resource_entry_points'