chore(pin): deprecate multi tracer support

[mabdinur]

Motivation

In ddtrace v3.0 ddtrace will drop support for initializing multiple instance of ddtrace.Tracer. With this change the all pin objects will use the same tracer instance. There is no need to support initializing, cloning or overriding the Pin.tracer argument.

Changes

• Deprecates the tracer argument in Pin.override(..), Pin.__init__(...), and Pin.clone(...)
• Avoids logging the new deprecation warning in integrations when the global tracer is used.

Checklist

• PR author has checked that all the criteria below are met
• The PR description includes an overview of the change
• The PR description articulates the motivation for the change
• The change includes tests OR the PR description describes a testing strategy
• The PR description notes risks associated with the change, if any
• Newly-added code is easy to change
• The change follows the library release note guidelines
• The change includes or references documentation updates if necessary
• Backport labels are set (if applicable)

Reviewer Checklist

• Reviewer has checked that all the criteria below are met
• Title is accurate
• All changes are related to the pull request's stated goal
• Avoids breaking API changes
• Testing strategy adequately addresses listed risks
• Newly-added code is easy to change
• Release note makes sense to a user of the library
• If necessary, author has acknowledged and discussed the performance implications of this PR as reported in the benchmarks PR comment
• Backport labels are set in a manner that is consistent with the release branch maintenance policy

[github-actions]

CODEOWNERS have been resolved as:

releasenotes/notes/remove-multi-tracer-support-from-pin-f2f20ca3fa731929.yaml  @DataDog/apm-python
ddtrace/contrib/grpc/__init__.py                                        @DataDog/apm-core-python @DataDog/apm-idm-python
ddtrace/contrib/internal/django/patch.py                                @DataDog/apm-core-python @DataDog/apm-idm-python
ddtrace/contrib/internal/mongoengine/trace.py                           @DataDog/apm-core-python @DataDog/apm-idm-python
ddtrace/contrib/internal/pylibmc/client.py                              @DataDog/apm-core-python @DataDog/apm-idm-python
ddtrace/contrib/internal/sqlalchemy/engine.py                           @DataDog/apm-core-python @DataDog/apm-idm-python
ddtrace/contrib/internal/tornado/application.py                         @DataDog/apm-core-python @DataDog/apm-idm-python
ddtrace/contrib/vertica/__init__.py                                     @DataDog/apm-core-python @DataDog/apm-idm-python
ddtrace/pin.py                                                          @DataDog/apm-sdk-api-python

[datadog-dd-trace-py-rkomorn]

Datadog Report

Branch report: munir/deprecate-using-pin-with-multiple-tracers
Commit report: 538935a
Test service: dd-trace-py

✅ 0 Failed, 279 Passed, 1276 Skipped, 4m 29.61s Total duration (34m 46.7s time saved)

[pr-commenter]

Benchmarks

Benchmark execution time: 2025-01-09 17:38:17

Comparing candidate commit 538935a in PR branch munir/deprecate-using-pin-with-multiple-tracers with baseline commit 35fe7b5 in branch main.

Found 0 performance improvements and 0 performance regressions! Performance is the same for 394 metrics, 2 unstable metrics.

[P403n1x87]

With multiple tracers gone, is there a chance that we can perhaps drop the concept of Pins entirely?