Fix allocate_sync usage with non-blocking streams #2165
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…eams. `allocate_sync` promises that the returned pointer is immediately valid on all streams. However, the previous implementation only allocated on the default stream without synchronizing it. This caused race conditions when using non-blocking streams, as the allocation might not be visible to other streams. This fix adds a synchronization of the default stream after allocation to ensure the pointer is immediately valid on all streams, including non-blocking streams. Closes rapidsai#2156.
wence-
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Nov 26, 2025
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| * The returned pointer is immediately valid on all streams. | ||
| * | ||
| * @throws rmm::bad_alloc When the requested `bytes` cannot be allocated. |
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Maybe add a note to deallocate_sync that "All stream-ordered work on ptr must be complete before calling this function otherwise behavior is undefined"?
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Description
allocate_syncpromises that the returned pointer is immediately valid on all streams. However, the previous implementation only allocated on the default stream without synchronizing it. This caused race conditions when using non-blocking streams, as the allocation might not be visible to other streams.This fix adds a synchronization of the default stream after allocation to ensure the pointer is immediately valid on all streams, including non-blocking streams.
Closes #2156.
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