[None] [fix] Disable UCC as WAR to MPI allgather issue before NGC PyTorch 25.12 upgrade (#9126)

Signed-off-by: Kaiyu Xie <[email protected]>

Author: kaiyux

tensorrt_llm/__init__.py

@@ -13,12 +13,16 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import os
+
+# Disable UCC to WAR allgather issue before NGC PyTorch 25.12 upgrade.
+os.environ["OMPI_MCA_coll_ucc_enable"] = "0"
+
 
 def _add_trt_llm_dll_directory():
     import platform
     on_windows = platform.system() == "Windows"
     if on_windows:
-        import os
         import sysconfig
         from pathlib import Path
         os.add_dll_directory(