… tests (#40403)

This PR enables Python 3.14 in all the different tests - Basic tests (Native Python tests), Bazel tests and Distrib tests to build Python 3.14 artifacts. In addition, it also updates all the public facing METADATA versions.

## Distribtests
Required pre-requisite changes to enable 3.14 artifacts are covered in #40289 .

## Bazel tests
Enabling Python 3.14 required updating the rules_python version to a more recent version that supports 3.14. This was done in #40602

## Basic tests
The following errors were caught by the Basic tests when running via Python 3.14 and resolved in this PR:

### 1) No running event loop for AsyncIO when run outside an async function
```
Traceback (most recent call last):
  File "src/python/grpcio/grpc/_cython/_cygrpc/aio/common.pyx.pxi", line 184, in grpc._cython.cygrpc.get_working_loop
RuntimeError: no running event loop
```
This was caught by the `tests_aio.unit.outside_init_test.TestOutsideInit` and `tests_aio.unit.init_test.TestInit` tests, and was also previously reported in #39507 with the root cause.

Following some investigation, the fix is being worked on by @sergiitk  in PR #40293. In order to parallelize the fix and this PR, these 2 tests are currently being skipped for Python 3.14 and above.

### 2) Pickling error from the `multiprocessing` library
```
_pickle.PicklingError: Can't pickle <function _test_well_known_types at 0x7f3937eee610>: it's not the same object as tests.unit._dynamic_stubs_test._test_well_known_types
when serializing dict item '_target'
when serializing multiprocessing.context.Process state
when serializing multiprocessing.context.Process object
```
This was caught by the `tests.unit._dynamic_stubs_test.DynamicStubTest` which runs test cases in a subprocess using the `multiprocessing` library.
Error root cause:
- The default start method of multiprocessing in linux has changed to `forkserver` instead of `fork` from Python 3.14.
- `forkserver` has a few extra restrictions for picklability as compared to `fork` (Ref: [Python Docs](https://docs.python.org/3.14/library/multiprocessing.html#the-spawn-and-forkserver-start-methods))
- All the [test case functions](https://github.com/grpc/grpc/blob/0243842d5d10f624bf8f09f45026dd300805502f/src/python/grpcio_tests/tests/unit/_dynamic_stubs_test.py#L115) in the DynamicStubTest that are provided as `target` to the `multiprocessing.Process` use decorators. This causes problems when pickling them.

Hence to resolve this, we manually set the 'start method' of `multiprocessing` to use the `fork` start method.

Closes #40403

PiperOrigin-RevId: 804290760

…ts (grpc#40289)

This PR adds Python 3.14 support for Distribtests by updating relevant docker images and distribtest build files for Linux, MacOS and Windows environments. However, artifact generation in distribtests will be enabled in the next PR grpc#40403

Prerequisites merged before this PR:
- grpc#40317
- grpc#40354
- grpc#40383

Closes grpc#40289

COPYBARA_INTEGRATE_REVIEW=grpc#40289 from sreenithi:python_314_test_support 3b8bf96
PiperOrigin-RevId: 802967999

…ts (grpc#40289)

This PR adds Python 3.14 support for Distribtests by updating relevant docker images and distribtest build files for Linux, MacOS and Windows environments. However, artifact generation in distribtests will be enabled in the next PR grpc#40403

Prerequisites merged before this PR:
- grpc#40317
- grpc#40354
- grpc#40383

Closes grpc#40289

COPYBARA_INTEGRATE_REVIEW=grpc#40289 from sreenithi:python_314_test_support 3b8bf96
PiperOrigin-RevId: 802967999

…ters for distribtests (#40637)

Backport of #40289 to v1.75.x.
---
This PR adds Python 3.14 support for Distribtests by updating relevant
docker images and distribtest build files for Linux, MacOS and Windows
environments. However, artifact generation in distribtests will be
enabled in the next PR #40403

Prerequisites merged before this PR:
- #40317
- #40354
- #40383

…ts (grpc#40289)

This PR adds Python 3.14 support for Distribtests by updating relevant docker images and distribtest build files for Linux, MacOS and Windows environments. However, artifact generation in distribtests will be enabled in the next PR grpc#40403

Prerequisites merged before this PR:
- grpc#40317
- grpc#40354
- grpc#40383

Closes grpc#40289

COPYBARA_INTEGRATE_REVIEW=grpc#40289 from sreenithi:python_314_test_support 3b8bf96
PiperOrigin-RevId: 802967999

… tests (grpc#40403)

This PR enables Python 3.14 in all the different tests - Basic tests (Native Python tests), Bazel tests and Distrib tests to build Python 3.14 artifacts. In addition, it also updates all the public facing METADATA versions.

## Distribtests
Required pre-requisite changes to enable 3.14 artifacts are covered in grpc#40289 .

## Bazel tests
Enabling Python 3.14 required updating the rules_python version to a more recent version that supports 3.14. This was done in grpc#40602

## Basic tests
The following errors were caught by the Basic tests when running via Python 3.14 and resolved in this PR:

### 1) No running event loop for AsyncIO when run outside an async function
```
Traceback (most recent call last):
  File "src/python/grpcio/grpc/_cython/_cygrpc/aio/common.pyx.pxi", line 184, in grpc._cython.cygrpc.get_working_loop
RuntimeError: no running event loop
```
This was caught by the `tests_aio.unit.outside_init_test.TestOutsideInit` and `tests_aio.unit.init_test.TestInit` tests, and was also previously reported in grpc#39507 with the root cause.

Following some investigation, the fix is being worked on by @sergiitk  in PR grpc#40293. In order to parallelize the fix and this PR, these 2 tests are currently being skipped for Python 3.14 and above.

### 2) Pickling error from the `multiprocessing` library
```
_pickle.PicklingError: Can't pickle <function _test_well_known_types at 0x7f3937eee610>: it's not the same object as tests.unit._dynamic_stubs_test._test_well_known_types
when serializing dict item '_target'
when serializing multiprocessing.context.Process state
when serializing multiprocessing.context.Process object
```
This was caught by the `tests.unit._dynamic_stubs_test.DynamicStubTest` which runs test cases in a subprocess using the `multiprocessing` library.
Error root cause:
- The default start method of multiprocessing in linux has changed to `forkserver` instead of `fork` from Python 3.14.
- `forkserver` has a few extra restrictions for picklability as compared to `fork` (Ref: [Python Docs](https://docs.python.org/3.14/library/multiprocessing.html#the-spawn-and-forkserver-start-methods))
- All the [test case functions](https://github.com/grpc/grpc/blob/0243842d5d10f624bf8f09f45026dd300805502f/src/python/grpcio_tests/tests/unit/_dynamic_stubs_test.py#L115) in the DynamicStubTest that are provided as `target` to the `multiprocessing.Process` use decorators. This causes problems when pickling them.

Hence to resolve this, we manually set the 'start method' of `multiprocessing` to use the `fork` start method.

Closes grpc#40403

PiperOrigin-RevId: 804290760

… tests (grpc#40403)

This PR enables Python 3.14 in all the different tests - Basic tests (Native Python tests), Bazel tests and Distrib tests to build Python 3.14 artifacts. In addition, it also updates all the public facing METADATA versions.
Required pre-requisite changes to enable 3.14 artifacts are covered in grpc#40289 .
Enabling Python 3.14 required updating the rules_python version to a more recent version that supports 3.14. This was done in grpc#40602
The following errors were caught by the Basic tests when running via Python 3.14 and resolved in this PR:
```
Traceback (most recent call last):
  File "src/python/grpcio/grpc/_cython/_cygrpc/aio/common.pyx.pxi", line 184, in grpc._cython.cygrpc.get_working_loop
RuntimeError: no running event loop
```
This was caught by the `tests_aio.unit.outside_init_test.TestOutsideInit` and `tests_aio.unit.init_test.TestInit` tests, and was also previously reported in grpc#39507 with the root cause.

Following some investigation, the fix is being worked on by @sergiitk  in PR grpc#40293. In order to parallelize the fix and this PR, these 2 tests are currently being skipped for Python 3.14 and above.
```
_pickle.PicklingError: Can't pickle <function _test_well_known_types at 0x7f3937eee610>: it's not the same object as tests.unit._dynamic_stubs_test._test_well_known_types
when serializing dict item '_target'
when serializing multiprocessing.context.Process state
when serializing multiprocessing.context.Process object
```
This was caught by the `tests.unit._dynamic_stubs_test.DynamicStubTest` which runs test cases in a subprocess using the `multiprocessing` library.
Error root cause:
- The default start method of multiprocessing in linux has changed to `forkserver` instead of `fork` from Python 3.14.
- `forkserver` has a few extra restrictions for picklability as compared to `fork` (Ref: [Python Docs](https://docs.python.org/3.14/library/multiprocessing.html#the-spawn-and-forkserver-start-methods))
- All the [test case functions](https://github.com/grpc/grpc/blob/0243842d5d10f624bf8f09f45026dd300805502f/src/python/grpcio_tests/tests/unit/_dynamic_stubs_test.py#L115) in the DynamicStubTest that are provided as `target` to the `multiprocessing.Process` use decorators. This causes problems when pickling them.

Hence to resolve this, we manually set the 'start method' of `multiprocessing` to use the `fork` start method.

Closes grpc#40403

PiperOrigin-RevId: 804290760

#40726)

Backport of #40403 to v1.75.x.
---
This PR enables Python 3.14 in all the different tests - Basic tests
(Native Python tests), Bazel tests and Distrib tests to build Python
3.14 artifacts. In addition, it also updates all the public facing
METADATA versions.

## Distribtests
Required pre-requisite changes to enable 3.14 artifacts are covered in
#40289 .

## Bazel tests
Enabling Python 3.14 required updating the rules_python version to a
more recent version that supports 3.14. This was done in #40602

## Basic tests
The following errors were caught by the Basic tests when running via
Python 3.14 and resolved in this PR:

### 1) No running event loop for AsyncIO when run outside an async
function
```
Traceback (most recent call last):
  File "src/python/grpcio/grpc/_cython/_cygrpc/aio/common.pyx.pxi", line 184, in grpc._cython.cygrpc.get_working_loop
RuntimeError: no running event loop
```
This was caught by the
`tests_aio.unit.outside_init_test.TestOutsideInit` and
`tests_aio.unit.init_test.TestInit` tests, and was also previously
reported in #39507 with the root cause.

Following some investigation, the fix is being worked on by @sergiitk in
PR #40293. In order to parallelize the fix and this PR, these 2 tests
are currently being skipped for Python 3.14 and above.

### 2) Pickling error from the `multiprocessing` library
```
_pickle.PicklingError: Can't pickle <function _test_well_known_types at 0x7f3937eee610>: it's not the same object as tests.unit._dynamic_stubs_test._test_well_known_types
when serializing dict item '_target'
when serializing multiprocessing.context.Process state
when serializing multiprocessing.context.Process object
```
This was caught by the `tests.unit._dynamic_stubs_test.DynamicStubTest`
which runs test cases in a subprocess using the `multiprocessing`
library.
Error root cause:
- The default start method of multiprocessing in linux has changed to
`forkserver` instead of `fork` from Python 3.14.
- `forkserver` has a few extra restrictions for picklability as compared
to `fork` (Ref: [Python
Docs](https://docs.python.org/3.14/library/multiprocessing.html#the-spawn-and-forkserver-start-methods))
- All the [test case
functions](https://github.com/grpc/grpc/blob/0243842d5d10f624bf8f09f45026dd300805502f/src/python/grpcio_tests/tests/unit/_dynamic_stubs_test.py#L115)
in the DynamicStubTest that are provided as `target` to the
`multiprocessing.Process` use decorators. This causes problems when
pickling them.

Hence to resolve this, we manually set the 'start method' of
`multiprocessing` to use the `fork` start method.