wip

Author: LostInDarkMath

pedantic/decorators/fn_deco_in_subprocess.py

@@ -8,7 +8,7 @@
     from multiprocess import Process, Pipe
     from multiprocess.connection import Connection
 
-    mp.set_start_method(method="spawn", force=True)
+    mp.set_start_method(method="spawn", force=True)  # child processes are fresh, no memory or state is inherited
 except ImportError:
     Process: Optional[Type] = None
     Pipe: Optional[Type] = None
@@ -33,6 +33,12 @@ def in_subprocess(func: Callable[..., Union[T, Awaitable[T]]]) -> Callable[...,
         of your application synchronously. That ensures that other asyncio.Tasks can work without any problem
         at the same time.
 
+        IMPORTANT! All *args and **kwargs passed to your function must be serializable with dill
+        https://pypi.org/project/dill, e.g. the following must work:
+        >>> import dill as pickle
+        >>> obj = 42  # can be anything
+        >>> assert pickle.loads(pickle.dumps(obj)) == obj
+
         Example:
             >>> import time
             >>> import asyncio
@@ -109,14 +115,9 @@ async def calculate_in_subprocess(func: Callable[..., Union[T, Awaitable[T]]], *
 def _inner(tx: Connection, fun: Callable[..., Union[T, Awaitable[T]]], *a, **kw_args) -> None:
     """ This runs in another process. """
 
-    event_loop = None
-    if inspect.iscoroutinefunction(fun):
-        event_loop = asyncio.new_event_loop()
-        asyncio.set_event_loop(event_loop)
-
     try:
-        if event_loop is not None:
-            res = event_loop.run_until_complete(fun(*a, **kw_args))
+        if inspect.iscoroutinefunction(fun):
+            res = asyncio.run(fun(*a, **kw_args))
         else:
             res = fun(*a, **kw_args)
     except Exception as ex:

pedantic/tests/test_in_subprocess.py

@@ -3,6 +3,7 @@
 import unittest
 from typing import NoReturn
 
+import dill
 from multiprocess import Pipe
 
 from pedantic import in_subprocess
@@ -150,3 +151,20 @@ def f(a: int, b: int) -> int:
         foo = Foo()
         assert await foo.pos_args() == 9
         assert await foo.kw_args() == 9
+
+    async def test_unpicklable_arg(self):
+        class NonPickableObject:
+            def __getstate__(self):
+                raise TypeError("This object cannot be pickled")
+
+        obj = NonPickableObject()
+
+        with self.assertRaises(expected_exception=TypeError):
+            dill.dumps(obj)
+
+        @in_subprocess
+        def f(x: NonPickableObject):
+            return x
+
+        with self.assertRaises(expected_exception=TypeError):
+            await f(obj)