…onGH-135295)

pythongh-126631: pythongh-137996: fix pre-loading of `__main__`

The `main_path` parameter was renamed `init_main_from_name`, update the
forkserver code accordingly.  This was leading to slower startup times when people
were trying to preload the main module.

---------
(cherry picked from commit 0912b3a)

Co-authored-by: Duane Griffin <[email protected]>
Co-authored-by: Gregory P. Smith <[email protected]>

pythonGH-135295)

pythongh-126631: pythongh-137996: fix pre-loading of `__main__`

The `main_path` parameter was renamed `init_main_from_name`, update the
forkserver code accordingly.  This was leading to slower startup times when people
were trying to preload the main module.

---------
(cherry picked from commit 0912b3a)

Co-authored-by: Duane Griffin <[email protected]>
Co-authored-by: Gregory P. Smith <[email protected]>

#138609)

gh-126631: gh-137996: fix pre-loading of `__main__`

The `main_path` parameter was renamed `init_main_from_name`, update the
forkserver code accordingly.  This was leading to slower startup times when people
were trying to preload the main module.

---------
(cherry picked from commit 0912b3a)

Co-authored-by: Duane Griffin <[email protected]>

…onGH-135295)

pythongh-126631: pythongh-137996: fix pre-loading of `__main__`

The `main_path` parameter was renamed `init_main_from_name`, update the
forkserver code accordingly.  This was leading to slower startup times when people
were trying to preload the main module.

---------

Co-authored-by: Gregory P. Smith <[email protected]>

#138607)

gh-126631: gh-137996: fix pre-loading of `__main__` (GH-135295)

gh-126631: gh-137996: fix pre-loading of `__main__`

The `main_path` parameter was renamed `init_main_from_name`, update the
forkserver code accordingly.  This was leading to slower startup times when people
were trying to preload the main module.

---------
(cherry picked from commit 0912b3a)

Co-authored-by: Duane Griffin <[email protected]>
Co-authored-by: Gregory P. Smith <[email protected]>
Co-authored-by: Petr Viktorin <[email protected]>
Co-authored-by: Gregory P. Smith <[email protected]>

…er_preload` (GH-141859)

Add a keyword-only `on_error` parameter to `multiprocessing.set_forkserver_preload()`. This allows the user to have exceptions during optional `forkserver` start method module preloading cause the forkserver subprocess to warn (generally to stderr) or exit with an error (preventing use of the forkserver) instead of being silently ignored.

This _also_ fixes an oversight, errors when preloading a `__main__` module are now treated the similarly. Those would always raise unlike other modules in preload, but that had gone unnoticed as up until bug fix PR GH-135295 in 3.14.1 and 3.13.8, the `__main__` module was never actually preloaded.

Based on original work by Nick Neumann @aggieNick02 in GH-99515.