Fix worker exit cleanup (#6450)

* working but ugly

* comments

* proper but hanging in grpc server destructor

* grpc server shutdown deadline

* fix disconnect

* lint

* shutdown_only in test

* replace shutdown

python/ray/_raylet.pyx

@@ -688,6 +688,8 @@ cdef execute_task(
         # If we've reached the max number of executions for this worker, exit.
         task_counter = manager.get_task_counter(job_id, function_descriptor)
         if task_counter == execution_info.max_calls:
+            # Intentionally disconnect so the raylet doesn't print an error.
+            # TODO(edoakes): we should handle max_calls in the core worker.
             worker.core_worker.disconnect()
             sys.exit(0)
 
@@ -737,11 +739,6 @@ cdef CRayStatus check_signals() nogil:
     return CRayStatus.OK()
 
 
-cdef void exit_handler() nogil:
-    with gil:
-        sys.exit(0)
-
-
 cdef shared_ptr[CBuffer] string_to_buffer(c_string& c_str):
     cdef shared_ptr[CBuffer] empty_metadata
     if c_str.size() == 0:
@@ -787,7 +784,7 @@ cdef class CoreWorker:
             raylet_socket.encode("ascii"), job_id.native(),
             gcs_options.native()[0], log_dir.encode("utf-8"),
             node_ip_address.encode("utf-8"), node_manager_port,
-            task_execution_handler, check_signals, exit_handler, True))
+            task_execution_handler, check_signals, True))
 
     def disconnect(self):
         self.destory_event_loop_if_exists()