Commits on Dec 19, 2022

1. pythongh-100344: Provide C implementation for asyncio.current_task …

   Implementing it in C makes it about 4x-6x faster
   
   Microbenchmark:
   
   ```
    # bench.py
   
   import time
   import timeit
   import asyncio
   
   ITERS: int = 10**6
   NANO: int = 10**9
   NANO_PER_ITER: float = NANO / ITERS
   
   async def main():
      # avoid load attr noise
      py_current_task = asyncio.tasks._py_current_task
      c_current_task = asyncio.tasks._c_current_task
   
      asyncio.current_task() # warmup
      py_current_task() # warmup
      c_current_task() # warmup
   
      print(
         "current_task: {}ns".format(timeit.timeit(py_current_task, number=ITERS, timer=time.process_time) * NANO_PER_ITER)
      )
      print(
         "current_task: {}ns".format(timeit.timeit(c_current_task, number=ITERS, timer=time.process_time) * NANO_PER_ITER)
      )
   
   asyncio.run(main())
   ```
   
   a few runs on MacBook Pro
   2.4 GHz 8-Core Intel Core i9
   64 GB 2667 MHz DDR4:
   
   debug build:
   
   ```
   ~/work/pyexe/main-dbg ⌚ 9:57:34
   $ ./python.exe bench.py
   [py] current_task: 606.234ns
   [c] current_task: 104.47699999999993ns
   
   ~/work/pyexe/main-dbg ⌚ 9:57:59
   $ ./python.exe bench.py
   [py] current_task: 631.856ns
   [c] current_task: 110.22500000000002ns
   
   ~/work/pyexe/main-dbg ⌚ 9:58:08
   $ ./python.exe bench.py
   [py] current_task: 637.746ns
   [c] current_task: 105.03899999999999ns
   
   ~/work/pyexe/main-dbg ⌚ 9:58:16
   $ ./python.exe bench.py
   [py] current_task: 621.3169999999999ns
   [c] current_task: 103.01300000000002ns
   ```
   
   opt build:
   
   ```
   ~/work/pyexe/main-opt ⌚ 10:33:17
   $ ./python.exe bench.py
   [py] current_task: 128.743ns
   [c] current_task: 31.997999999999998ns
   
   ~/work/pyexe/main-opt ⌚ 10:33:24
   $ ./python.exe bench.py
   [py] current_task: 126.388ns
   [c] current_task: 32.64599999999998ns
   
   ~/work/pyexe/main-opt ⌚ 10:33:26
   $ ./python.exe bench.py
   [py] current_task: 137.053ns
   [c] current_task: 32.066999999999986ns
   
   ~/work/pyexe/main-opt ⌚ 10:33:28
   $ ./python.exe bench.py
   [py] current_task: 131.17800000000003ns
   [c] current_task: 32.06600000000001ns
   ```

   

   itamaro committed Dec 19, 2022
   76cbbc6