[PR] [Bugfix][NCCL] Release NCCL thread_local resources in destructor [tvm]

["Lunderberg (via GitHub)" <gi...@apache.org>]

Lunderberg opened a new pull request, #17078:
URL: https://github.com/apache/tvm/pull/17078

   Prior to this commit, allocations performed by `ncclCommInitRank` had no corresponding call to `ncclCommDestroy`.  While `ncclCommDestroy` does occur in the `CCLThreadLocalContext::Clear` method, there are no calls into this method.  On worker processes, the failure to call `ncclCommDestroy` typically had little effect.  Any destruction would occur shortly before the process closes, and so resources would be reclaimed by the OS when the process terminates.
   
   However, worker0 of a Disco session is a separate thread, rather than a separate process.  While this allows it to easily receive data from the controller thread, resources allocated by worker0 are not reclaimed by the OS until the entire process terminates.  As a result, the `CCLThreadLocalContext` leaked GPU memory, as the `ncclCommInitRank` call at the start of each
   `tvm.runtime.disco.ProcessSession` was never de-allocated.  The increase in GPU memory usage was about 1 gigabyte for each `ProcessSession`.
   
   This commit updates `CCLThreadLocalContext` to have a destructor that calls the `Clear` method.  For worker0, this is called when the thread is joined to the main thread.


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Re: [PR] [Bugfix][NCCL] Release NCCL thread_local resources in destructor [tvm]

["vinx13 (via GitHub)" <gi...@apache.org>]

vinx13 merged PR #17078:
URL: https://github.com/apache/tvm/pull/17078


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