[Bugfix][ROCm] Fixing trying to import non-existent symbols from libnccl.so (#25605)

Signed-off-by: Gregory Shtrasberg <Gregory.Shtrasberg@amd.com>

vllm/distributed/device_communicators/pynccl_wrapper.py

@@ -30,7 +30,9 @@ from typing import Any, Optional
 import torch
 from torch.distributed import ReduceOp
 
+from vllm import envs
 from vllm.logger import init_logger
+from vllm.platforms import current_platform
 from vllm.utils import find_nccl_library
 
 logger = init_logger(__name__)
@@ -275,10 +277,27 @@ class NCCLLibrary:
         if so_file not in NCCLLibrary.path_to_dict_mapping:
             _funcs: dict[str, Any] = {}
             for func in NCCLLibrary.exported_functions:
+                try:
                     f = getattr(self.lib, func.name)
                     f.restype = func.restype
                     f.argtypes = func.argtypes
                     _funcs[func.name] = f
+                except AttributeError:
+                    if func.name in [
+                            "ncclCommWindowRegister",
+                            "ncclCommWindowDeregister"
+                    ]:
+                        if envs.VLLM_USE_NCCL_SYMM_MEM:
+                            logger.warning_once(
+                                "The symbol %s is not found in the NCCL "
+                                "library %s. To enable VLLM_USE_NCCL_SYMM_MEM "
+                                " please update your NCCL version to >= "
+                                "2.27.03.", func.name, so_file)
+                        if current_platform.is_rocm():
+                            # Having an exception here on ROCm platform is
+                            # not allowed during graph capturing
+                            continue
+                    raise
             NCCLLibrary.path_to_dict_mapping[so_file] = _funcs
         self._funcs = NCCLLibrary.path_to_dict_mapping[so_file]