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bugfix: Setting OMPI_MPI_THREAD_LEVEL to a value different than requested crashes #13211

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Setting OMPI_MPI_THREAD_LEVEL to a value different than requested in MPI_Init_thread would invoke the error handler, even though it is an useful override in some threaded library use cases.

@abouteiller abouteiller removed the bug label Apr 25, 2025
@abouteiller abouteiller force-pushed the bugfix/env-thread-level-ignored branch 4 times, most recently from b71461f to b481893 Compare April 25, 2025 16:29
@abouteiller abouteiller requested review from jsquyres and bosilca May 5, 2025 15:33
*/
if (NULL != (env = getenv("OMPI_MPI_THREAD_LEVEL"))) {
int env_required = atoi(env);
err_arg_required = err_arg_required ||
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env_arg_required |= ...etc

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My biggest concern here is that the user is required to know the valid thread level values as defined in the MPI ABI header. We should keep doing what we do right now, aka 0-3, and use a shift operation to convert it to the ABI value env_required = (1 << (10 + atoi(env)));

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For now, the valid values are still [0-3] (because our internal ABI is not the same as the standardized ABI (yet?), I'll add this consideration to the comment requested by Jeff so we don't forget when the time comes.

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FWIW: we plan to support both the existing OMPI ABI and the official MPI Forum MPI ABI. Hence, we'll probably want code that can handle both situations.

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the important part is that we don't want the users to have to enter the ABI values for the environment variable for the thread level. We want this to remain indexed as it is today.

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Hmm. Good point.

Maybe we should also accept strings? MPI_THREAD_SINGLE, MPI_THREAD_MULTIPLE, ... etc. I.e., something that doesn't depend on a numeric value.

@abouteiller abouteiller force-pushed the bugfix/env-thread-level-ignored branch from b481893 to 1a0d2f7 Compare May 12, 2025 17:42
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Hello! The Git Commit Checker CI bot found a few problems with this PR:

1a0d2f7: review comments

  • check_signed_off: does not contain a valid Signed-off-by line

Please fix these problems and, if necessary, force-push new commits back up to the PR branch. Thanks!

@abouteiller abouteiller force-pushed the bugfix/env-thread-level-ignored branch from 1a0d2f7 to 8ad7579 Compare May 12, 2025 17:48
`requested` in `MPI_Init_thread` would invoke the error handler, even
though it is an useful override in some threaded library use cases.

Signed-off-by: Aurelien Bouteiller <[email protected]>
@abouteiller abouteiller force-pushed the bugfix/env-thread-level-ignored branch from 8ad7579 to fe5d20e Compare May 15, 2025 15:55
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OMPI_MPI_THREAD_LEVEL cannot override 'required' in MPI_Init_thread
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