[Bug] Fix FlashInfer MNNVL socket collisions under concurrent vLLM jobs (#36674)

Signed-off-by: yewentao256 <zhyanwentao@126.com>

vllm/distributed/device_communicators/flashinfer_all_reduce.py

@@ -3,6 +3,8 @@
 
 
 import atexit
+import os
+import random
 import threading
 
 import torch
@@ -67,15 +69,20 @@ def initialize_fi_ar_workspace(
 
     backend = envs.VLLM_FLASHINFER_ALLREDUCE_BACKEND
     comm_backend = TorchDistBackend(group=group)
-    _fi_ar_workspace = flashinfer_comm.create_allreduce_fusion_workspace(
-        backend=backend,
-        world_size=world_size,
-        rank=rank,
-        max_token_num=max_token_num,
-        hidden_dim=hidden_dim,
-        dtype=dtype,
-        comm_backend=comm_backend,
-    )
+    rng_state = random.getstate()
+    try:
+        random.seed(int.from_bytes(os.urandom(16), byteorder="big"))
+        _fi_ar_workspace = flashinfer_comm.create_allreduce_fusion_workspace(
+            backend=backend,
+            world_size=world_size,
+            rank=rank,
+            max_token_num=max_token_num,
+            hidden_dim=hidden_dim,
+            dtype=dtype,
+            comm_backend=comm_backend,
+        )
+    finally:
+        random.setstate(rng_state)
     assert _fi_ar_workspace is not None
     logger.debug(
         "Initialized FlashInfer All Reduce workspace: backend=%s, "