Is it possible to use Python3
asyncio package with
C++ extension that builds with
Boost.Python. And functions that are written in
C++ can work really long time. I want to use
asyncio to call these functions but
res = await cpp_function() code doesn't work.
<li>What happens when
cpp_functionis called inside coroutine?</li> <li>How not get blocked by calling
C++function that works very long time?</li> </ul>
C++ doesn't do some I/O operations, just calculations.
What happens when cpp_function is called inside coroutine?
If you call long-running Python/C function inside any of your coroutines, it freezes your event loop (freezes all coroutines everywhere).
You should avoid this situation.
How not get blocked by calling C++ function that works very long time
You should use run_in_executor to run you function in separate thread or process.
run_in_executor returns coroutine that you can await.
You'll probably need
ProcessPoolExecutor because of GIL (I'm not sure if
ThreadPoolExecutor is option in your situation, but I advice you to check it).
Here's example of awaiting long-running code:
import asyncio from concurrent.futures import ProcessPoolExecutor import time def blocking_function(): # Function with long-running C/Python code. time.sleep(3) return True async def main(): # Await of executing in other process, # it doesn't block your event loop: loop = asyncio.get_event_loop() res = await loop.run_in_executor(executor, blocking_function) if __name__ == '__main__': executor = ProcessPoolExecutor(max_workers=1) # Prepare your executor somewhere. loop = asyncio.new_event_loop() asyncio.set_event_loop(loop) try: loop.run_until_complete(main()) finally: loop.run_until_complete(loop.shutdown_asyncgens()) loop.close()