[core] (cgroups 21/n) Do not move dashboard modules into the workers cgroup even if they are drivers

python/ray/tests/resource_isolation/test_resource_isolation_integration.py

@@ -1,6 +1,8 @@
 import os
 import platform
+import subprocess
 import sys
+import textwrap
 from pathlib import Path
 from typing import Set
 
@@ -11,6 +13,7 @@
 import ray._common.utils as utils
 import ray._private.ray_constants as ray_constants
 import ray.scripts.scripts as scripts
+from ray._common.test_utils import wait_for_condition
 from ray._private.resource_isolation_config import ResourceIsolationConfig
 
 # These tests are intended to run in CI inside a container.
@@ -21,7 +24,6 @@
 # Run these commands locally before running the test suite:
 #
 #  sudo mkdir -p /sys/fs/cgroup/resource_isolation_test
-#  echo "+cpu +memory" | sudo tee -a /sys/fs/cgroup/resource_isolation_test/cgroup.subtree_control
 #  sudo chown -R $(whoami):$(whoami) /sys/fs/cgroup/resource_isolation_test/
 #  sudo chmod -R u+rwx /sys/fs/cgroup/resource_isolation_test/
 #  echo $$ | sudo tee /sys/fs/cgroup/resource_isolation_test/cgroup.procs
@@ -337,6 +339,35 @@ def assert_cgroup_hierarchy_exists_for_node(
         )
 
 
+def assert_process_in_not_moved_into_ray_cgroups(
+    node_id: str,
+    resource_isolation_config: ResourceIsolationConfig,
+    pid: str,
+):
+    """Asserts that the system processes were created in the correct cgroup.
+
+    Args:
+        node_id: used to construct the path of the cgroup subtree
+        resource_isolation_config: used to construct the path of the cgroup
+            subtree
+        pid:
+    """
+    base_cgroup_for_node = resource_isolation_config.cgroup_path
+    node_cgroup = Path(base_cgroup_for_node) / f"ray-node_{node_id}"
+    cgroup_procs_file_paths = [
+        node_cgroup / "system" / "leaf" / "cgroup.procs",
+        node_cgroup / "user" / "non-ray" / "cgroup.procs",
+        node_cgroup / "user" / "workers" / "cgroup.procs",
+    ]
+    found_pid = False
+    for file_path in cgroup_procs_file_paths:
+        with open(file_path, "r") as cgroup_procs_file:
+            lines = cgroup_procs_file.readlines()
+            for line in lines:
+                found_pid = found_pid or (line.strip() == pid)
+    assert not found_pid
+
+
 def assert_system_processes_are_in_system_cgroup(
     node_id: str,
     resource_isolation_config: ResourceIsolationConfig,
@@ -407,6 +438,30 @@ def assert_cgroup_hierarchy_cleaned_up_for_node(
     ), f"Root cgroup node at {node_cgroup} was not deleted. Cgroup cleanup failed. You may have to manually delete the cgroup subtree."
 
 
+def create_driver_in_internal_namespace():
+    """
+    Returns a driver process that is a part of the '_ray_internal_' namespace.
+    If the driver is part of the '_ray_internal_' namespace, it will NOT
+    be moved into the workers cgroup by the raylet when it registers.
+    The Dashboard ServeHead and JobHead modules are drivers that are
+    technically system processes and use the '_ray_internal_' namespace and therefore
+    must not be moved into the workers cgroup on registration.
+    """
+
+    driver_code = textwrap.dedent(
+        """
+        import ray
+        import time
+        ray.init(namespace='_ray_internal_')
+        time.sleep(3600)
+    """
+    ).strip()
+
+    second_driver_proc = subprocess.Popen(["python", "-c", driver_code])
+
+    return second_driver_proc
+
+
 # The following tests check for cgroup setup and cleanup with the
 # ray cli.
 def test_ray_cli_start_invalid_resource_isolation_config(cleanup_ray):
@@ -465,13 +520,16 @@ def __init__(self):
         def get_pid(self):
             return os.getpid()
 
+    second_driver_proc = create_driver_in_internal_namespace()
+
     actor_refs = []
     for _ in range(num_cpus):
         actor_refs.append(Actor.remote())
     worker_pids = set()
     worker_pids.add(str(os.getpid()))
     for actor in actor_refs:
         worker_pids.add(str(ray.get(actor.get_pid.remote())))
+
     assert_system_processes_are_in_system_cgroup(
         node_id,
         resource_isolation_config,
@@ -480,8 +538,13 @@ def get_pid(self):
     assert_worker_processes_are_in_workers_cgroup(
         node_id, resource_isolation_config, worker_pids
     )
-    runner.invoke(scripts.stop)
+    assert_process_in_not_moved_into_ray_cgroups(
+        node_id, resource_isolation_config, second_driver_proc.pid
+    )
 
+    second_driver_proc.kill()
+    wait_for_condition(lambda: second_driver_proc.wait(), timeout=5)
+    runner.invoke(scripts.stop)
     assert_cgroup_hierarchy_cleaned_up_for_node(node_id, resource_isolation_config)
 
 

src/ray/raylet/node_manager.cc

@@ -1278,10 +1278,6 @@ Status NodeManager::RegisterForNewDriver(
   worker->SetProcess(Process::FromPid(pid));
   rpc::JobConfig job_config;
   job_config.ParseFromString(message->serialized_job_config()->str());
-  Status s = cgroup_manager_->AddProcessToWorkersCgroup(std::to_string(pid));
-  RAY_CHECK(s.ok()) << absl::StrFormat(
-      "Failed to move the driver process into the workers cgroup with error %s",
-      s.ToString());
   return worker_pool_.RegisterDriver(worker, job_config, send_reply_callback);
 }
 

src/ray/raylet/worker_pool.cc

@@ -846,6 +846,10 @@ Status WorkerPool::RegisterWorker(const std::shared_ptr<WorkerInterface> &worker
   return Status::OK();
 }
 
+bool IsInternalNamespace(const std::string &ray_namespace) {
+  return absl::StartsWith(ray_namespace, kRayInternalNamespacePrefix);
+}
+
 void WorkerPool::OnWorkerStarted(const std::shared_ptr<WorkerInterface> &worker) {
   auto &state = GetStateForLanguage(worker->GetLanguage());
   const StartupToken worker_startup_token = worker->GetStartupToken();
@@ -907,6 +911,13 @@ Status WorkerPool::RegisterDriver(const std::shared_ptr<WorkerInterface> &driver
   auto &state = GetStateForLanguage(driver->GetLanguage());
   state.registered_drivers.insert(std::move(driver));
   const auto job_id = driver->GetAssignedJobId();
+  // A subset of the Ray Dashboard Modules are registered as drivers under an
+  // internal namespace. These are system processes and therefore, do not need to be moved
+  // into the workers cgroup.
+  if (!IsInternalNamespace(job_config.ray_namespace())) {
+    add_to_cgroup_hook_(std::to_string(driver->GetProcess().GetId()));
+  }
+
   HandleJobStarted(job_id, job_config);
 
   if (driver->GetLanguage() == Language::JAVA) {
@@ -1657,10 +1668,6 @@ bool WorkerPool::IsWorkerAvailableForScheduling() const {
   return false;
 }
 
-bool IsInternalNamespace(const std::string &ray_namespace) {
-  return absl::StartsWith(ray_namespace, kRayInternalNamespacePrefix);
-}
-
 std::vector<std::shared_ptr<WorkerInterface>> WorkerPool::GetAllRegisteredDrivers(
     bool filter_dead_drivers, bool filter_system_drivers) const {
   std::vector<std::shared_ptr<WorkerInterface>> drivers;