Fix doc, always check ray runtime_env

Signed-off-by: Vasily Litvinov <fam1ly.n4me@yandex.ru>

docs/getting_started/troubleshooting.rst

@@ -291,10 +291,6 @@ or
     df = pd.DataFrame([0, 1, 2, 3])
     print(df)
 
-.. _issue: https://github.com/modin-project/modin/issues
-.. _Slack: https://modin.org/slack.html
-
-
 Spurious error "cannot import partially initialised pandas module" on custom Ray cluster
 """"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
 
@@ -329,3 +325,6 @@ Modin sets up automatically on the Ray clusters it spawns, but it might be missi
 
 So if you're seeing the issue like shown above, please make sure you set this environment variable on all
 worker nodes of your cluster before actually spawning the workers.
+
+.. _issue: https://github.com/modin-project/modin/issues
+.. _Slack: https://modin.org/slack.html

modin/core/execution/ray/common/utils.py

@@ -167,14 +167,16 @@ def initialize_ray(
             if not GPU_MANAGERS:
                 for i in range(GpuCount.get()):
                     GPU_MANAGERS.append(GPUManager.remote(i))
-    else:  # ray is already initialized, check runtime env config
-        env_vars = ray.get_runtime_context().runtime_env.get("env_vars", {})
-        for varname, varvalue in extra_init_kw["runtime_env"]["env_vars"].items():
-            if str(env_vars.get(varname, "")) != str(varvalue):
-                ErrorMessage.single_warning(
-                    "When using a pre-initialized Ray cluster, please ensure that the runtime env "
-                    + f"sets environment variable {varname} to {varvalue}"
-                )
+
+    # Now ray is initialized, check runtime env config - especially useful if we join
+    # an externally pre-configured cluster
+    env_vars = ray.get_runtime_context().runtime_env.get("env_vars", {})
+    for varname, varvalue in extra_init_kw["runtime_env"]["env_vars"].items():
+        if str(env_vars.get(varname, "")) != str(varvalue):
+            ErrorMessage.single_warning(
+                "When using a pre-initialized Ray cluster, please ensure that the runtime env "
+                + f"sets environment variable {varname} to {varvalue}"
+            )
 
     num_cpus = int(ray.cluster_resources()["CPU"])
     num_gpus = int(ray.cluster_resources().get("GPU", 0))