FEAT-modin-project#4574: Warn when pre-initialized Ray cluster is not…

… using all available memory

Signed-off-by: Rehan Durrani <[email protected]>

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

@@ -219,6 +219,17 @@ def initialize_ray(
             if not GPU_MANAGERS:
                 for i in range(GpuCount.get()):
                     GPU_MANAGERS.append(GPUManager.remote(i))
+    else:
+        ray_obj_store_mem = ray.available_resources()["object_store_memory"]
+        virtual_memory = psutil.virtual_memory().total
+        if (ray_obj_store_mem // 1e9) < (0.6 * virtual_memory) // 1e9:
+            warnings.warn(
+                "Modin has detected that it is running on a pre-initialized Ray cluster. "
+                + f"This cluster has currently allocated {ray_obj_store_mem // 1e9} GB for its "
+                + f"object store, but the device has {virtual_memory // 1e9} GB of RAM available. "
+                + "Modin recommends initializing Ray with at least 60% of available RAM to prevent "
+                + "Out Of Memory errors."
+            )
     _move_stdlib_ahead_of_site_packages()
     ray.worker.global_worker.run_function_on_all_workers(
         _move_stdlib_ahead_of_site_packages