Fix None process group appended in _fuse_input_dist_splits #3547
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Summary: We identified this potential bug during debugging issue reported in https://fb.workplace.com/groups/755371733754414/permalink/833999072850393/ Fixed a bug in `_fuse_input_dist_splits` where names with no valid process group (pg=None) were being added to `names_per_pg[None]`. This would cause issues downstream when trying to create `FusedKJTListSplitsAwaitable` with a None process group. The issue occurred when: 1. A request is of type `KJTListSplitsAwaitable` 2. None of its awaitables are of type `KJTSplitsAllToAllMeta` 3. This leaves `pg = None` (line 207) 4. The name was still appended to `names_per_pg[None]` (line 213) The fix adds a check to only append names when `pg is not None`, ensuring that only requests with valid process groups are included in the fused operations. Why this matters: - Prevents passing `pg=None` to `FusedKJTListSplitsAwaitable` (line 232) - Ensures only valid distributed operations are fused together - Avoids potential runtime errors or undefined behavior Differential Revision: D87110878
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@YongzhongYang has exported this pull request. If you are a Meta employee, you can view the originating Diff in D87110878. |
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Summary:
We identified this potential bug during debugging issue reported in https://fb.workplace.com/groups/755371733754414/permalink/833999072850393/
Fixed a bug in
_fuse_input_dist_splitswhere names with no valid processgroup (pg=None) were being added to
names_per_pg[None]. This would causeissues downstream when trying to create
FusedKJTListSplitsAwaitablewitha None process group.
The issue occurred when:
KJTListSplitsAwaitableKJTSplitsAllToAllMetapg = None(line 207)names_per_pg[None](line 213)The fix adds a check to only append names when
pg is not None, ensuringthat only requests with valid process groups are included in the fused
operations.
Why this matters:
pg=NonetoFusedKJTListSplitsAwaitable(line 232)Differential Revision: D87110878