Copy pythonGH-98137, make some changes, add benchmarking script, tryi…

…ng to get it working

Lib/asyncio/__init__.py

@@ -36,7 +36,34 @@
            tasks.__all__ +
            threads.__all__ +
            timeouts.__all__ +
-           transports.__all__)
+           transports.__all__ + (
+            'create_eager_task_factory',
+            'eager_task_factory',
+           ))
+
+def create_eager_task_factory(custom_task_constructor):
+
+    def factory(loop, coro, *, name=None, context=None):
+        loop._check_closed()
+        try:
+            result = coro.send(None)
+        except StopIteration as si:
+            print("XXX")
+            fut = loop.create_future()
+            fut.set_result(si.value)
+            return fut
+        except Exception as ex:
+            print("YYY")
+            fut = loop.create_future()
+            fut.set_exception(ex)
+            return fut
+        else:
+            return custom_task_constructor(
+                coro, loop=loop, name=name, context=context, yield_result=result)
+
+    return factory
+
+eager_task_factory = create_eager_task_factory(Task)
 
 if sys.platform == 'win32':  # pragma: no cover
     from .windows_events import *

Lib/asyncio/base_events.py

@@ -447,6 +447,38 @@ def create_task(self, coro, *, name=None, context=None):
 
         return task
 
+    def eager_task_factory(self, coro, *, name=None, context=None):
+        """Start a coroutine.
+
+        This runs the coroutine until it first suspends itself.
+
+        If it runs till completion or fails without suspending,
+        return a future with the result or exception.
+
+        Otherwise schedule the resumption and return a task.
+        """
+        self._check_closed()
+        # Do not go through the task factory.
+        # This _is_ the task factory.
+        if tasks.Task is not tasks._PyTask:
+            task = tasks.Task(coro, loop=self, name=name, context=context)
+        else:
+            try:
+                yield_result = coro.send(None)
+            except BaseException as exc:
+                fut = self.create_future()
+                # XXX What about AsyncStopIteration?
+                if isinstance(exc, StopIteration):
+                    fut.set_result(exc.value)
+                else:
+                    fut.set_exception(exc)
+                return fut
+            task = tasks.Task(coro, loop=self, name=name, context=context,
+                                    yield_result=yield_result)
+        if task._source_traceback:
+            del task._source_traceback[-1]
+        return task
+
     def set_task_factory(self, factory):
         """Set a task factory that will be used by loop.create_task().
 

Lib/asyncio/taskgroups.py

@@ -141,11 +141,14 @@ def create_task(self, coro, *, name=None, context=None):
             raise RuntimeError(f"TaskGroup {self!r} is finished")
         if self._aborting:
             raise RuntimeError(f"TaskGroup {self!r} is shutting down")
-        if context is None:
+        if hasattr(self._loop, "eager_task_factory"):
+            task = self._loop.eager_task_factory(coro, name=name, context=context)
+        elif context is None:
             task = self._loop.create_task(coro)
         else:
             task = self._loop.create_task(coro, context=context)
-        tasks._set_task_name(task, name)
+        if not task.done():  # If it's done already, it's a future
+            tasks._set_task_name(task, name)
         task.add_done_callback(self._on_task_done)
         self._tasks.add(task)
         return task

Lib/asyncio/tasks.py

@@ -75,6 +75,8 @@ def _set_task_name(task, name):
             set_name(name)
 
 
+_NOT_SET = object()
+
 class Task(futures._PyFuture):  # Inherit Python Task implementation
                                 # from a Python Future implementation.
 
@@ -93,7 +95,8 @@ class Task(futures._PyFuture):  # Inherit Python Task implementation
     # status is still pending
     _log_destroy_pending = True
 
-    def __init__(self, coro, *, loop=None, name=None, context=None):
+    def __init__(self, coro, *, loop=None, name=None, context=None,
+                                coro_result=None, yield_result=_NOT_SET):
         super().__init__(loop=loop)
         if self._source_traceback:
             del self._source_traceback[-1]
@@ -117,7 +120,10 @@ def __init__(self, coro, *, loop=None, name=None, context=None):
         else:
             self._context = context
 
-        self._loop.call_soon(self.__step, context=self._context)
+        if yield_result is _NOT_SET:
+            self._loop.call_soon(self.__step, context=self._context)
+        else:
+            self.__step2(yield_result)
         _register_task(self)
 
     def __del__(self):
@@ -287,6 +293,12 @@ def __step(self, exc=None):
         except BaseException as exc:
             super().set_exception(exc)
         else:
+            self.__step2(result)
+        finally:
+            _leave_task(self._loop, self)
+            self = None  # Needed to break cycles when an exception occurs.
+
+    def __step2(self, result):
             blocking = getattr(result, '_asyncio_future_blocking', None)
             if blocking is not None:
                 # Yielded Future must come from Future.__iter__().
@@ -333,9 +345,6 @@ def __step(self, exc=None):
                 new_exc = RuntimeError(f'Task got bad yield: {result!r}')
                 self._loop.call_soon(
                     self.__step, new_exc, context=self._context)
-        finally:
-            _leave_task(self._loop, self)
-            self = None  # Needed to break cycles when an exception occurs.
 
     def __wakeup(self, future):
         try:
@@ -357,13 +366,13 @@ def __wakeup(self, future):
 _PyTask = Task
 
 
-try:
-    import _asyncio
-except ImportError:
-    pass
-else:
-    # _CTask is needed for tests.
-    Task = _CTask = _asyncio.Task
+# try:
+#     import _asyncio
+# except ImportError:
+#     pass
+# else:
+#     # _CTask is needed for tests.
+#     Task = _CTask = _asyncio.Task
 
 
 def create_task(coro, *, name=None, context=None):

async_tree.py

@@ -0,0 +1,187 @@
+# Copyright (c) Facebook, Inc. and its affiliates. (http://www.facebook.com)
+"""
+Benchmark script for recursive async tree workloads. This script includes the
+following microbenchmark scenarios:
+
+1) "no_suspension": No suspension in the async tree.
+2) "suspense_all": Suspension (simulating IO) at all leaf nodes in the async tree.
+3) "memoization": Simulated IO calls at all leaf nodes, but with memoization. Only
+                  un-memoized IO calls will result in suspensions.
+4) "cpu_io_mixed": A mix of CPU-bound workload and IO-bound workload (with
+                   memoization) at the leaf nodes.
+
+Use the commandline flag or choose the corresponding <Scenario>AsyncTree class
+to run the desired microbenchmark scenario.
+"""
+
+
+import asyncio
+import math
+import random
+import time
+from argparse import ArgumentParser
+
+
+NUM_RECURSE_LEVELS = 6
+NUM_RECURSE_BRANCHES = 6
+IO_SLEEP_TIME = 0.05
+DEFAULT_MEMOIZABLE_PERCENTAGE = 90
+DEFAULT_CPU_PROBABILITY = 0.5
+FACTORIAL_N = 500
+
+
+def parse_args():
+    parser = ArgumentParser(
+        description="""\
+Benchmark script for recursive async tree workloads. It can be run as a standalone
+script, in which case you can specify the microbenchmark scenario to run and whether
+to print the results.
+"""
+    )
+    parser.add_argument(
+        "-s",
+        "--scenario",
+        choices=["no_suspension", "suspense_all", "memoization", "cpu_io_mixed"],
+        default="no_suspension",
+        help="""\
+Determines which microbenchmark scenario to run. Defaults to no_suspension. Options:
+1) "no_suspension": No suspension in the async tree.
+2) "suspense_all": Suspension (simulating IO) at all leaf nodes in the async tree.
+3) "memoization": Simulated IO calls at all leaf nodes, but with memoization. Only
+                  un-memoized IO calls will result in suspensions.
+4) "cpu_io_mixed": A mix of CPU-bound workload and IO-bound workload (with
+                   memoization) at the leaf nodes.
+""",
+    )
+    parser.add_argument(
+        "-m",
+        "--memoizable-percentage",
+        type=int,
+        default=DEFAULT_MEMOIZABLE_PERCENTAGE,
+        help="""\
+Sets the percentage (0-100) of the data that should be memoized, defaults to 90. For
+example, at the default 90 percent, data 1-90 will be memoized and data 91-100 will not.
+""",
+    )
+    parser.add_argument(
+        "-c",
+        "--cpu-probability",
+        type=float,
+        default=DEFAULT_CPU_PROBABILITY,
+        help="""\
+Sets the probability (0-1) that a leaf node will execute a cpu-bound workload instead
+of an io-bound workload. Defaults to 0.5. Only applies to the "cpu_io_mixed"
+microbenchmark scenario.
+""",
+    )
+    parser.add_argument(
+        "-p",
+        "--print",
+        action="store_true",
+        default=False,
+        help="Print the results (runtime and number of Tasks created).",
+    )
+    return parser.parse_args()
+
+
+class AsyncTree:
+    def __init__(
+        self,
+        memoizable_percentage=DEFAULT_MEMOIZABLE_PERCENTAGE,
+        cpu_probability=DEFAULT_CPU_PROBABILITY,
+    ):
+        self.suspense_count = 0
+        self.task_count = 0
+        self.memoizable_percentage = memoizable_percentage
+        self.cpu_probability = cpu_probability
+        self.cache = {}
+        # set to deterministic random, so that the results are reproducible
+        random.seed(0)
+
+    async def mock_io_call(self):
+        self.suspense_count += 1
+        await asyncio.sleep(IO_SLEEP_TIME)
+
+    def create_task(self, loop, coro):
+        self.task_count += 1
+        return asyncio.Task(coro, loop=loop)
+
+    async def suspense_func(self):
+        raise NotImplementedError(
+            "To be implemented by each microbenchmark's derived class."
+        )
+
+    async def recurse(self, recurse_level):
+        if recurse_level == 0:
+            await self.suspense_func()
+            return
+
+        await asyncio.gather(
+            *[self.recurse(recurse_level - 1) for _ in range(NUM_RECURSE_BRANCHES)]
+        )
+
+    def run(self):
+        loop = asyncio.new_event_loop()
+        # eager_factory = asyncio.create_eager_task_factory(self.create_task)
+        # loop.set_task_factory(eager_factory)
+        loop.set_task_factory(asyncio.eager_task_factory)
+        loop.run_until_complete(self.recurse(NUM_RECURSE_LEVELS))
+        loop.close()
+
+
+class NoSuspensionAsyncTree(AsyncTree):
+    async def suspense_func(self):
+        return
+
+
+class SuspenseAllAsyncTree(AsyncTree):
+    async def suspense_func(self):
+        await self.mock_io_call()
+
+
+class MemoizationAsyncTree(AsyncTree):
+    async def suspense_func(self):
+        # deterministic random (seed preset)
+        data = random.randint(1, 100)
+
+        if data <= self.memoizable_percentage:
+            if self.cache.get(data):
+                return data
+
+            self.cache[data] = True
+
+        await self.mock_io_call()
+        return data
+
+
+class CpuIoMixedAsyncTree(MemoizationAsyncTree):
+    async def suspense_func(self):
+        if random.random() < self.cpu_probability:
+            # mock cpu-bound call
+            return math.factorial(FACTORIAL_N)
+        else:
+            return await MemoizationAsyncTree.suspense_func(self)
+
+
+if __name__ == "__main__":
+    args = parse_args()
+    scenario = args.scenario
+
+    trees = {
+        "no_suspension": NoSuspensionAsyncTree,
+        "suspense_all": SuspenseAllAsyncTree,
+        "memoization": MemoizationAsyncTree,
+        "cpu_io_mixed": CpuIoMixedAsyncTree,
+    }
+    async_tree_class = trees[scenario]
+    async_tree = async_tree_class(args.memoizable_percentage, args.cpu_probability)
+
+    start_time = time.perf_counter()
+    async_tree.run()
+    end_time = time.perf_counter()
+
+    if args.print:
+        print(f"Scenario: {scenario}")
+        print(f"Time: {end_time - start_time} s")
+        print(f"Tasks created: {async_tree.task_count}")
+        print(f"Suspense called: {async_tree.suspense_count}")