Fix TypeError in os.fork() for garbage-collected processors

[pranaysb]

Description

Fixes TypeError: 'NoneType' object is not callable in os.fork() when a BatchProcessor or PeriodicExportingMetricReader has been garbage collected.

The after_in_child callbacks registered via os.register_at_fork during initialization stored weak references to reinit methods, but unconditionally invoked them without checking if the reference had resolved to None. This PR adds a safe _after_in_child method that checks for None before invoking the callback, matching the existing behavior of ConcurrentMultiSpanProcessor.

Fixes #5452

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

How Has This Been Tested?

Verified via the existing test suite and added specific unit tests verifying that garbage-collected processors do not crash the child process upon fork.

• test_garbage_collected_processor_does_not_crash_on_fork in tests/shared_internal/test_batch_processor.py
• test_garbage_collected_processor_does_not_crash_on_fork in tests/metrics/test_periodic_exporting_metric_reader.py

Does This PR Require a Contrib Repo Change?

• Yes. - Link to PR:
• No.

Checklist:

• Followed the style guidelines of this project
• Changelogs have been updated
• Unit tests have been added
• Documentation has been updated

[Copilot]

Pull request overview

This PR fixes a TypeError: 'NoneType' object is not callable that can occur during os.fork() when at-fork callbacks are registered via os.register_at_fork using weakref.WeakMethod, and the underlying processor/reader instance has been garbage collected. The change updates the at-fork callback implementations to safely no-op when the weak reference has expired, aligning behavior with existing fork-handling patterns in the SDK.

Changes:

• Guard os.register_at_fork(after_in_child=...) callbacks so weakly-referenced bound methods are only invoked when still alive.
• Add fork-focused regression tests for BatchProcessor and PeriodicExportingMetricReader to ensure no unraisable exception is emitted to stderr after GC.
• Add a targeted pylint suppression in a log export test; add changelog entry.

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 6 comments.

Show a summary per file

File	Description
opentelemetry-sdk/src/opentelemetry/sdk/_shared_internal/init.py	Makes BatchProcessor’s at-fork callback safe when the weak method has expired.
opentelemetry-sdk/src/opentelemetry/sdk/metrics/_internal/export/init.py	Makes PeriodicExportingMetricReader’s at-fork callback safe when the weak method has expired.
opentelemetry-sdk/tests/shared_internal/test_batch_processor.py	Adds a regression test that forks after GC and asserts no TypeError is printed to stderr.
opentelemetry-sdk/tests/metrics/test_periodic_exporting_metric_reader.py	Adds a regression test that forks after GC and asserts no TypeError is printed to stderr.
opentelemetry-sdk/tests/logs/test_export.py	Adds an inline pylint suppression for an intentional “too few args” logging call in a test.
.changelog/5453.fixed	Documents the bugfix in the changelog system.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[aabmass]

Please resolve comments if you feel they're addressed, and we can take another review pass

[pranaysb]

Please resolve comments if you feel they're addressed, and we can take another review pass

addressed the review feedback and pushed a fix for the skip-condition gap. all threads resolved