instantiate dask client inside BaseScheduler, remove dask client inje…

…ction into scheduler class at extension launch

conftest.py

@@ -60,7 +60,6 @@ def jp_scheduler(jp_scheduler_db_url, jp_scheduler_root_dir, jp_scheduler_db):
         db_url=jp_scheduler_db_url,
         root_dir=str(jp_scheduler_root_dir),
         environments_manager=MockEnvironmentManager(),
-        dask_client_future=AsyncMock(),
     )
 
 

jupyter_scheduler/extension.py

@@ -1,3 +1,5 @@
+import asyncio
+
 from dask.distributed import Client as DaskClient
 from jupyter_core.paths import jupyter_data_dir
 from jupyter_server.extension.application import ExtensionApp
@@ -72,15 +74,11 @@ def initialize_settings(self):
 
         environments_manager = self.environment_manager_class()
 
-        asyncio_loop = self.serverapp.io_loop.asyncio_loop
-        dask_client_future = asyncio_loop.create_task(self._get_dask_client())
-
         scheduler = self.scheduler_class(
             root_dir=self.serverapp.root_dir,
             environments_manager=environments_manager,
             db_url=self.db_url,
             config=self.config,
-            dask_client_future=dask_client_future,
         )
 
         job_files_manager = self.job_files_manager_class(scheduler=scheduler)
@@ -89,28 +87,8 @@ def initialize_settings(self):
             environments_manager=environments_manager,
             scheduler=scheduler,
             job_files_manager=job_files_manager,
-            dask_client_future=dask_client_future,
         )
 
         if scheduler.task_runner:
-            asyncio_loop.create_task(scheduler.task_runner.start())
-
-    async def _get_dask_client(self):
-        """Creates and configures a Dask client."""
-        return DaskClient(processes=False, asynchronous=True)
-
-    async def stop_extension(self):
-        """Called by the Jupyter Server when stopping to cleanup resources."""
-        try:
-            await self._stop_extension()
-        except Exception as e:
-            self.log.error("Error while stopping Jupyter Scheduler:")
-            self.log.exception(e)
-
-    async def _stop_extension(self):
-        """Closes the Dask client if it exists."""
-        if "dask_client_future" in self.settings:
-            dask_client: DaskClient = await self.settings["dask_client_future"]
-            self.log.info("Closing Dask client.")
-            await dask_client.close()
-            self.log.info("Dask client closed.")
+            loop = asyncio.get_event_loop()
+            loop.create_task(scheduler.task_runner.start())

jupyter_scheduler/scheduler.py

@@ -1,3 +1,4 @@
+import asyncio
 import os
 import random
 import shutil
@@ -100,14 +101,19 @@ def __init__(
         self,
         root_dir: str,
         environments_manager: Type[EnvironmentManager],
-        dask_client_future: Awaitable[DaskClient],
         config=None,
         **kwargs,
     ):
         super().__init__(config=config, **kwargs)
         self.root_dir = root_dir
         self.environments_manager = environments_manager
-        self.dask_client_future = dask_client_future
+
+        loop = asyncio.get_event_loop()
+        self.dask_client_future: Awaitable[DaskClient] = loop.create_task(self._get_dask_client())
+
+    async def _get_dask_client(self):
+        """Creates and configures a Dask client."""
+        return DaskClient(processes=False, asynchronous=True)
 
     def create_job(self, model: CreateJob) -> str:
         """Creates a new job record, may trigger execution of the job.