[Bugfix] Set VLLM_ALLREDUCE_USE_SYMM_MEM default to False (#24696)

Signed-off-by: yewentao256 <[email protected]>

Author: yewentao256

vllm/envs.py

@@ -1218,7 +1218,7 @@ def get_vllm_port() -> Optional[int]:
 
     # Whether to use pytorch symmetric memory for allreduce
     "VLLM_ALLREDUCE_USE_SYMM_MEM":
-    lambda: bool(int(os.getenv("VLLM_ALLREDUCE_USE_SYMM_MEM", "1"))),
+    lambda: bool(int(os.getenv("VLLM_ALLREDUCE_USE_SYMM_MEM", "0"))),
 
     # Allows vllm to find tuned config under customized folder
     "VLLM_TUNED_CONFIG_FOLDER":