Make dill optional

[claudevdm]

Make dill an optional dependency.

1. Installing apache-beam[dill] requires dill==0.3.1.1
2. If pickle_library=dill, dill==0.3.1.1 is required
3. If pickle_library=dill_unsafe, any version of dill is supported
4. Add pytest marker + tox environment for dill tests.
5. Add dill 0.3.1.1 to base manual requirements. This is for convenience if users forget to pass it as an additional requirement, but still allows different versions of dill.

There will be two followup PR's

1. Github actions workflow file for dill tests
2. Remove runtime checks for dill version and flag to override the dill version for coder case, so that tests that do not really depend on dill but have a FastPrimitivesCoder.as_deterministic_coder invocation dont need to run in the dill actions worklflow (e.g. reshuffle tests, bigquery file loads test)

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[gemini-code-assist]

Summary of Changes

Hello @claudevdm, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request refactors the dependency on the 'dill' serialization library, making it optional rather than a core requirement for the Apache Beam Python SDK. This change provides greater flexibility for users who may not need 'dill' in their pipelines, while ensuring that its use is properly validated and supported when explicitly chosen. The update also introduces a mechanism for using potentially unsupported 'dill' versions for advanced users.

Highlights

• Dependency Management: The 'dill' library is no longer a mandatory dependency for the Apache Beam Python SDK. It has been moved to an optional extra, meaning users can install it via apache-beam[dill] if their pipelines require it.
• Dill Usage and Validation: The system now includes runtime checks to ensure 'dill' is installed when a DillCoder or dill pickler is explicitly used. If 'dill' is missing, a RuntimeError or ImportError is raised with instructions on how to install it.
• Pickle Library Options: A new pickle_library option, dill_unsafe, has been introduced. This allows users to bypass the strict version validation for 'dill' (which typically requires dill==0.3.1.1), enabling the use of other 'dill' versions at their own risk.
• Test Suite Updates: Numerous tests that rely on 'dill' have been updated to conditionally skip if 'dill' is not installed. A new pytest marker uses_dill and a dedicated tox environment (py{version}-dill) have been added to manage and run these 'dill'-dependent tests.

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[github-actions]

Checks are failing. Will not request review until checks are succeeding. If you'd like to override that behavior, comment assign set of reviewers

[claudevdm]

/gemini review

[gemini-code-assist]

Code Review

This pull request effectively makes dill an optional dependency by removing it from the core requirements and adding it as an extra. The changes are comprehensive, touching runtime code to raise errors when dill is needed but absent, and updating numerous tests to skip gracefully. The addition of a dill_unsafe option and validation for the dill version is also a good improvement. My review includes a few suggestions to improve code clarity, fix a redundant check, and correct a docstring.

[claudevdm]

R: @damccorm

[github-actions]

Stopping reviewer notifications for this pull request: review requested by someone other than the bot, ceding control. If you'd like to restart, comment assign set of reviewers

[claudevdm]

Failing tests look like flakes and unrelated.

[damccorm]

Thanks, this LGTM. I re-kicked off some test suites, and will merge once those are green

[claudevdm]

Failing postcommit tests look related to #36027

[damccorm]

Failing postcommit tests look related to #36027

@liferoad could you please take a look?

[damccorm]

I do agree that this PR isn't causing the failures though, so merging

[liferoad]

some flaky ones from the logs:

# py310
[gw1] FAILED apache_beam/io/gcp/pubsub_integration_test.py::PubSubIntegrationTest::test_streaming_with_attributes 

# py39
[gw0] FAILED apache_beam/io/gcp/pubsub_integration_test.py::PubSubIntegrationTest::test_batch_write_data_only 

[liferoad]

PubSubIntegrationTest

trying #36140

[tvalentyn]

possible other ways to name this concept:

dill_any
dill_untested
dill_any_version

[claudevdm]

#21298