Python precommit flaky: Failed to read inputs in the data plane

[damccorm]

This error is affecting several different portable Python tests.

apache_beam.runners.portability.fn_api_runner.fn_runner_test.FnApiRunnerTestWithGrpcAndMultiWorkers.(test_sdf_default_truncate_when_unbounded|test_flatten) [1][2] flaked with error "Failed to read inputs in the data plane." because of GRPC exception "broken pipe". Later there is an exception "Channel closed prematurely."

https://ci-beam.apache.org/job/beam_PreCommit_Python_Phrase/2476/testReport/junit/apache_beam.runners.portability.fn_api_runner.fn_runner_test/FnApiRunnerTestWithGrpcAndMultiWorkers/test_flatten_3/

Imported from Jira BEAM-12322. Original Jira may contain additional context.
Reported by: ibzib.

[BjornPrime]

.take-issue

[BjornPrime]

.close-issue

[tvalentyn]

seems a duplicate of #21104.

[BjornPrime]

It looks like different specific tests are failing, though in the same class. Definitely could be related. Also interesting that Pablo managed to repro those by running the whole class. I'll give that a shot and see if it repros any of these.