[Asyncio] Remove async init legacy code (#8177)

* [Asyncio] Remove async init legacy code

* Fix places that call async_init

python/ray/_raylet.pyx

@@ -1142,8 +1142,8 @@ cdef class CoreWorker:
             asyncio.set_event_loop(self.async_event_loop)
             # Initialize the async plasma connection.
             # Delayed import due to async_api depends on _raylet.
-            from ray.experimental.async_api import _async_init
-            self.async_event_loop.run_until_complete(_async_init())
+            from ray.experimental.async_api import init as plasma_async_init
+            plasma_async_init()
 
             # Create and attach the monitor object
             monitor_state = AsyncMonitorState(self.async_event_loop)

python/ray/experimental/async_api.py

@@ -1,7 +1,4 @@
-# Note: asyncio is only compatible with Python 3
-
 import asyncio
-import threading
 
 import ray
 from ray.experimental.async_plasma import PlasmaEventHandler
@@ -10,7 +7,10 @@ from ray.services import logger
 handler = None
 
 
-async def _async_init():
+def init():
+    """Initialize plasma event handlers for asyncio support."""
+    assert ray.is_initialized(), "Please call ray.init before async_api.init"
+
     global handler
     if handler is None:
         worker = ray.worker.global_worker
@@ -20,31 +20,6 @@ async def _async_init():
         logger.debug("AsyncPlasma Connection Created!")
 
 
-def init():
-    """
-    Initialize synchronously.
-    """
-    assert ray.is_initialized(), "Please call ray.init before async_api.init"
-
-    # Noop when handler is set.
-    if handler is not None:
-        return
-
-    loop = asyncio.get_event_loop()
-    if loop.is_running():
-        if loop._thread_id != threading.get_ident():
-            # If the loop is runing outside current thread, we actually need
-            # to do this to make sure the context is initialized.
-            asyncio.run_coroutine_threadsafe(_async_init(), loop=loop)
-        else:
-            async_init_done = asyncio.get_event_loop().create_task(
-                _async_init())
-            # Block until the async init finishes.
-            async_init_done.done()
-    else:
-        asyncio.get_event_loop().run_until_complete(_async_init())
-
-
 def as_future(object_id):
     """Turn an object_id into a Future object.
 

python/ray/tests/test_asyncio.py

@@ -113,8 +113,8 @@ async def test_asyncio_get(ray_start_regular_shared, event_loop):
     loop.set_debug(True)
 
     # This is needed for async plasma
-    from ray.experimental.async_api import _async_init
-    await _async_init()
+    from ray.experimental.async_api import init
+    init()
 
     # Test Async Plasma
     @ray.remote