create_communicator_grouped2 may trigger uninit value memory issue(randomly crash) when you train more iterations.

[anderson101866]

Container:

nvcr.io/nvidia/pytorch:24.05-py3

Machine:

x86 CPU with A100 node

Reproduce:

python -m torch.distributed.run --nproc-per-node=2 examples/pytorch/comm_gemm_overlap/ln_mlp_with_overlap.py --num-iters=1000

It'll probably crash or not because at line 102, the operator= will trigger destructor to delete the old value std::function of _alloc_copy_allgather, which is actually an uninit value.
see also the definition of struct communicator

struct communicator {
...  
std::function<void(void **, void *, size_t, ExtComm)> _alloc_copy_allgather; //will not be initialized by malloc
std::function<void(ExtComm)> _barrier; //will not be initialized by malloc
std::function<void(void *)> _free; //will not be initialized by malloc

Hope this hint helps the progress.

[anderson101866]

The commit on this fork will fix this.
denera@7a9522b

[denera]

@anderson101866 This should be fixed now in TE/main as of PR #1087. Could you check and close the issue if resolved?

[anderson101866]

Yes, it’s resolved. Thanks for your greatly help!