[Debug] Add trigger to concurrent stage init (#1274)

Signed-off-by: tzhouam <tzhouam@connect.ust.hk>

vllm_omni/entrypoints/utils.py

@@ -280,3 +280,63 @@ def get_final_stage_id_for_e2e(
         final_stage_id_for_e2e = last_stage_id
 
     return final_stage_id_for_e2e
+
+
+# The following code detects if the process is running in a container and if
+# PID host is available. If so, we can use process-scoped memory tracking;
+# otherwise we need sequential init locks.
+
+
+def _read_text(path: str) -> str | None:
+    try:
+        with open(path, encoding="utf-8", errors="replace") as f:
+            return f.read()
+    except (FileNotFoundError, PermissionError, OSError):
+        return None
+
+
+def in_container() -> bool:
+    # Common Docker signal
+    if os.path.exists("/.dockerenv"):
+        return True
+
+    # cgroup markers (works for Docker/containerd/K8s/Podman in many setups)
+    cg = _read_text("/proc/1/cgroup") or ""
+    markers = ("docker", "containerd", "kubepods", "libpod", "podman")
+    return any(m in cg for m in markers)
+
+
+def has_pid_host() -> bool | None:
+    """
+    Returns:
+      True  -> very likely running with --pid=host (host PID namespace)
+      False -> very likely isolated PID namespace (default)
+      None  -> cannot determine
+    """
+    # Strong signal: in host pid namespace, PID 2 is usually kthreadd
+    comm2 = _read_text("/proc/2/comm")
+    if comm2 is not None:
+        comm2 = comm2.strip()
+        if comm2 == "kthreadd":
+            return True
+        # If PID 2 exists and is NOT kthreadd, we're almost certainly not in host pid ns
+        return False
+
+    # Fallback: check for other low-numbered kernel threads (best-effort)
+    for pid, name in [(3, "rcu_gp"), (4, "rcu_par_gp"), (10, "ksoftirqd/0")]:
+        comm = _read_text(f"/proc/{pid}/comm")
+        if comm is not None:
+            if comm.strip() == name:
+                return True
+            else:
+                return False
+
+    return False
+
+
+def detect_pid_host() -> bool:
+    ic = in_container()
+    if not ic:
+        return True
+
+    return has_pid_host()