Today `GroupRegistry` employs thread isolation by default, i.e. every thread sees its own process group registry. This is intended to work for one-device-per-process (for python use cases) and one-device-per-thread case (for custom native runtimes).
However, there's a problem - there are python use cases that initializes/registers process groups in one thread, and runs collectives in another thread. This use case should be supported. However, since `GroupRegistry` employs thread isolation by default, collectives in different threads can't find the registered process groups.
This PR fixes the issue by:
- Make `GroupRegistry` work in non-thread isolation mode by default. This would match the behavior w/o the native process group registry.
- Introduces `set_thread_isolation_mode` so one-device-per-thread runtimes can enable thread isolation mode explicitly.
Differential Revision: [D54658515](https://our.internmc.facebook.com/intern/diff/D54658515)
Pull Request resolved: https://github.com/pytorch/pytorch/pull/121457
Approved by: https://github.com/wanchaol
This diff introduces an env var `_USE_NATIVE_C10D_FUNCTIONAL` that tells `_functional_collective` to use native `c10d_functional` ops. The Python version and the native version will co-exist until we completely switch to the native version after more testing and verification.
NOTE: `DeviceMesh` support for native `c10d_functional` will be added in a subsequent PR.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/113057
Approved by: https://github.com/LucasLLC, https://github.com/wconstab, https://github.com/wanchaol
This PR introduces a native version of c10d_functional ops. The main goal is to add collective support in AOTInductor and allow collective ops to work in multi-threaded native runtimes.
The native version also incorporated API improvements we wished to implement in Python c10d_functional:
- Removed `ranks` and `group_size` from collective op signatures which were proven to be redundant.
- Use tensor storage as opposed to `void*` to resolve in-flight work.
The native process group registration/resolution mechansim is only used for native c10d_functional in the PR. It will become the single source of truth in upcoming PRs.
The upcoming PRs will implement Inductor/AOTInductor support for c10d_functional, after which native c10d_functional will replace Python c10d_functional.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/110570
Approved by: https://github.com/wanchaol
