How to multiprocess async/await functions in python? - python

I need to run an event every 60 seconds to all my cars. My problem with the code below is the while loop doesn't end until the timeout (60) does and hence only the first car in cars is run.
class RunCars(BaseEvent):
def __init__(self):
interval_seconds = 60 # Set the interval for this event
super().__init__(interval_seconds)
# run() method will be called once every {interval_seconds} minutes
async def run(self, client, cars):
for car in cars:
channel = get_channel(client, "general")
await client.send_message(channel, 'Running this '+str(car))
await msg.add_reaction(str(get_emoji(':smiley:')))
reaction = None
while True:
if str(reaction) == str(get_emoji(':smiley:'))
await client.send_message(channel, 'Finished with this '+str(car))
try:
reaction, user = await client.wait_for('reaction_add', timeout=60, check=check)
except:
break
I tried changing the code into a multithreaded process but had trouble with async/await inside the function and problems with pickling the function itself.
I'd appreciate any suggestions for how to go about this..

The asyncio module lets you execute multiple async method concurrently using the gather method. I think you can achieve the behavior you want by defining a method that runs a single car, and then replacing your for-loop with a call to gather, which will execute multiple run_one coroutines (methods) concurrently:
import asyncio
class RunCars(BaseEvent):
def __init__(self):
interval_seconds = 60 # Set the interval for this event
super().__init__(interval_seconds)
async def run(self, client, cars):
coroutines = [self.run_one(client, car) for car in cars]
asyncio.gather(*coroutines)
async def run_one(self, client, car):
channel = get_channel(client, "general")
await client.send_message(channel, 'Running this '+str(car))
await msg.add_reaction(str(get_emoji(':smiley:')))
reaction = None
while True:
if str(reaction) == str(get_emoji(':smiley:'))
await client.send_message(channel, 'Finished with this '+str(car))
try:
reaction, user = await client.wait_for('reaction_add', timeout=60, check=check)
except:
break
In general, when writing async code, you should try to replace sequential calls to async methods - basically for-loops that call async methods - with gather statements so they execute concurrently.

Related

Running asynchronous functions in non-asynchronous functions

I'm trying to run some asynchronous functions in her asynchronous function, the problem is, how did I understand that functions don't run like that, then how do I do it? I don't want to make the maze_move function asynchronous.
async def no_stop():
#some logic
await asyncio.sleep(4)
async def stop(stop_time):
await asyncio.sleep(stop_time)
#some logic
def maze_move():
no_stop()
stop(1.5)
async def main(websocket):
global data_from_client, data_from_server, power_l, power_r
get_params()
get_data_from_server()
get_data_from_client()
while True:
msg = await websocket.recv()
allow_data(msg)
cheker(data_from_client)
data_from_server['IsBrake'] = data_from_client['IsBrake']
data_from_server['powerL'] = power_l
data_from_server['powerR'] = power_r
await websocket.send(json.dumps(data_from_server))
print(data_from_client['IsBrake'])
start_server = websockets.serve(main, 'localhost', 8080)
asyncio.get_event_loop().run_until_complete(start_server)
asyncio.get_event_loop().run_forever()
How about:
def maze_move():
loop = asyncio.get_event_loop()
loop.run_until_complete(no_stop())
loop.run_until_complete(stop(1.5))
If you wanted to run two coroutines concurrently, then:
def maze_move():
loop = asyncio.get_event_loop()
loop.run_until_complete(asyncio.gather(no_stop(), stop(1.5)))
Update Based on Updated Question
I am guessing what it is you want to do (see my comment to your question):
First, you cannot call from maze_move coroutines such as stop directly since stop() does not result in calling stop it just returns a coroutine object. So maze_move has to be modified. I will assume you do not want to make it a coroutine itself (why not as long as you already have to modify it?). And further assuming you want to invoke maze_move from a coroutine that wishes to run concurrently other coroutines, then you can create a new coroutine, e.g. maze_move_runner that will run maze_move in a separate thread so that it does not block other concurrently running coroutines:
import asyncio
import concurrent.futures
async def no_stop():
#some logic
print('no stop')
await asyncio.sleep(4)
async def stop(stop_time):
await asyncio.sleep(stop_time)
print('stop')
#some logic
async def some_coroutine():
print('Enter some_coroutine')
await asyncio.sleep(2)
print('Exit some_coroutine')
return 1
def maze_move():
# In case we are being run directly and not in a separate thread:
try:
loop = asyncio.get_running_loop()
except:
# This thread has no current event loop, so:
loop = asyncio.new_event_loop()
asyncio.set_event_loop(loop)
loop.run_until_complete(no_stop())
loop.run_until_complete(stop(1.5))
return 'Done!'
async def maze_move_runner():
loop = asyncio.get_running_loop()
# Run in another thread:
return await loop.run_in_executor(None, maze_move)
async def main():
loop = asyncio.get_running_loop()
results = await (asyncio.gather(some_coroutine(), maze_move_runner()))
print(results)
asyncio.run(main())
Prints:
Enter some_coroutine
no stop
Exit some_coroutine
stop
[1, 'Done!']
But this would be the most straightforward solution:
async def maze_move():
await no_stop()
await stop(1.5)
return 'Done!'
async def main():
loop = asyncio.get_running_loop()
results = await (asyncio.gather(some_coroutine(), maze_move()))
print(results)
If you have an already running event loop, you can define an async function inside of a sync function and launch it as task:
def maze_move():
async def amaze_move():
await no_stop()
await stop(1.5)
return asyncio.create_task(amaze_move())
This function returns an asyncio.Task object which can be used in an await expression, or not, depending on requirements. This way you won't have to make maze_move itself an async function, although I don't know why that would be a goal. Only a async function can run no_stop and stop, so you've got to have an async function somewhere.

Python - Run multiple async functions simultaneously

I'm essentially making a pinger, that makes has a 2d list, of key / webhook pairs, and after pinging a key, send the response to a webhook
the 2d list goes as follows:
some_list = [["key1", "webhook1"], ["key2", "webhook2"]]
My program is essentially a loop, and I'm not too sure how I can rotate the some_list data, in the function.
Here's a little demo of what my script looks like:
async def do_ping(some_pair):
async with aiohttps.ClientSession() as s:
tasks = await gen_tasks(s, some_pair)
results = await asyncio.gather(*tasks*)
sleep(10)
await do_ping(some_pair)
I've tried:
async def main():
for entry in some_list:
asyncio.run(do_ping(entry))
but due to the do_ping function being a self-calling loop, it just calls the first one over and over again, and never gets to the ones after it. Hoping to find a solution to this, whether it's threading or alike, and if you have a better way of structuring some_list values (which I assume would be a dictionary), feel free to drop that feedback as well
You made your method recursive await do_ping(some_pair), it never ends for the loop in main to continue. I would restructure the application like this:
async def do_ping(some_pair):
async with aiohttps.ClientSession() as s:
while True:
tasks = await gen_tasks(s, some_pair)
results = await asyncio.gather(*tasks)
await asyncio.sleep(10)
async def main():
tasks = [do_ping(entry) for entry in some_list]
await asyncio.gather(*tasks)
if __name__ == "__main__":
asyncio.run(main())
Alternatively you could move the repeat and sleeping logic into the main:
async def do_ping(some_pair):
async with aiohttps.ClientSession() as s:
tasks = await gen_tasks(s, some_pair)
results = await asyncio.gather(*tasks)
async def main():
while True:
tasks = [do_ping(entry) for entry in some_list]
await asyncio.gather(*tasks)
await asyncio.sleep(10)
if __name__ == "__main__":
asyncio.run(main())
You could also start the tasks before doing a call to sleep, and gather them afterwards. That would make the pings more consistently start at 10 second intervals instead of being 10 seconds + the time it takes to gather the results:
async def main():
while True:
tasks = [
asyncio.create_task(do_ping(entry))
for entry in some_list
]
await asyncio.sleep(10)
await asyncio.wait(tasks)
EDIT As pointed out by creolo you should only create a single ClientSession object. See https://docs.aiohttp.org/en/stable/client_reference.html
Session encapsulates a connection pool (connector instance) and supports keepalives by default. Unless you are connecting to a large, unknown number of different servers over the lifetime of your application, it is suggested you use a single session for the lifetime of your application to benefit from connection pooling.
async def do_ping(session, some_pair):
tasks = await gen_tasks(session, some_pair)
results = await asyncio.gather(*tasks)
async def main():
async with aiohttp.ClientSession() as session:
while True:
tasks = [
asyncio.create_task(do_ping(session, entry))
for entry in some_list
]
await asyncio.sleep(10)
await asyncio.wait(tasks)

Why does discord.py block/buffer when awaiting an asyncio Queue?

The messages are sent in 'waves', i.e. nothing for a couple seconds and then ~5 nearly at the same time. I left out token and channel.
import discord, asyncio
class Bot(discord.Client):
def __init__(self, q, channel):
super().__init__()
self.q = q
self.channel_id = channel
self.bg_task = self.loop.create_task(self.send_messages())
async def on_message(self, message):
if message.author == self.user or message.channel.id != self.channel_id:
return
print(message.content)
async def send_messages(self):
await self.wait_until_ready()
channel = self.get_channel(self.channel_id)
while not self.is_closed():
msg = await self.q.get()
await channel.send(msg)
from threading import Thread
from time import sleep
q = asyncio.Queue()
def f():
while True:
q.put_nowait("hi")
sleep(2)
Thread(target=f).start()
bot = Bot(q, channel)
bot.run(token)
Weirdly, the on_message event seems unaffected, and also, replacing msg = await self.q.get() by
msg = "hi"
await asyncio.sleep(2)
seems to result in the expected behavior.
I'm not sure where things go wrong, so I kept the example more specific to Discord.
Edit
Expanding on the asyncio.sleep behavior, I have replaced the loop in send_messages by
if 0:
msg = await self.q.get()
else:
await asyncio.sleep(0.1)
if self.q.empty():
continue
msg = await self.q.get()
await channel.send(msg)
The if is just to toggle between the original and experiment.
Clearly, one would expect the else part to be at most as fast as the if part, however waiting for the queue to be non-empty seems to completely solve the issue.
I'm starting to think discord and a blocking asyncio Queue interact in unforeseen ways
On the other hand it seems that the channel.send is the blocking line, so maybe it also has something to do with rate.
This is because the rate limit for sending messages through Discord's API is 5 / 5 seconds.
That's why you're seeing 5 messages being sent at once and then a delay as the next messages are rate limited.

How to queue requests until the function returns a response for a previous request?

When the user sends !bot in a special channel, the code runs a function that runs for 20-30 seconds (depends on some_var). My problem is that if several people write !bot , the code will reverse this in multiple threads. How do I queue for these requests?
I tried to understand asyncio, discord.ext.tasks, but can't figure out how it works
#client.command()
async def test(ctx, *args):
data = args
if data:
answer = some_function(data[0]) #works from 5 seconds to 1 minute or more
await ctx.send(answer)
Everything works well, but I just don't want to load the system so much, I need a loop to process requests first in - first out
You can use an asyncio.Queue to queue tasks, then process them sequentially in a background loop:
import asyncio
from discord.ext import commands, tasks
queue = asyncio.Queue()
bot = commands.Bot('!')
#tasks.loop(seconds=1.0)
async def executor():
task = await queue.get()
await task
queue.task_done()
#executor.before_loop
async def before():
await bot.wait_until_ready()
#bot.command()
async def example(ctx, num: int):
await queue.put(helper(ctx, num))
async def helper(ctx, num):
await asyncio.sleep(num)
await ctx.send(num)
executor.start()
bot.run('token')
Make some_function() to async then await it. Then all test command will be processed simultaneously.
async some_function(...):
# something to do
#client.command()
async def test(ctx, *args):
if args:
answer = await some_function(data[0])
await ctx.send(answer)

Usage of threading.Timer with async based functions

I'm working on a Discord bot with Python and it queues music from YouTube, i'm working on something to autoqueue songs when the player is stopped, while all of the code works perfectly, the only problem is me not being able to check if the player is playing or not every 15 seconds
async def cmd_autoqueue(self,message, player,channel,author, permissions, leftover_args):
print("autoq ran")
if started == True:
if player.is_stopped:
await self.cmd_autoqadd(player, channel, author, permissions,leftover_args,song_url=last_url)
threading.Timer(15.0,await self.cmd_autoqueue(message, player,channel,author, permissions, leftover_args)).start()
i did realise that
threading.Timer(15.0,await self.cmd_autoqueue(message, player,channel,author, permissions, leftover_args)).start()
calls the function, and if i wanted to pass it as something that would be called later i would use lambda: but , async lambda?
also started boolean is managed by other stuff so well its there for the sake of the 'if', here in this question
Solution:
async def cmd_autoqueue(self,message, player,channel,author, permissions, leftover_args):
global started
print("loop")
if started == True:
await asyncio.sleep(15)
if player.is_stopped:
await self.cmd_autoqadd(player, channel, author, permissions,leftover_args,song_url=last_url)
await self.cmd_autoqueue(message, player,channel,author, permissions, leftover_args)
You could use loop.call_later, that returns you an asyncio-compatible handler to cancel the task.
class YourClass:
def init(self):
self._loop = asyncio.get_event_loop()
self._check_handler = None
def schedule_check(self):
self._check_handler = loop.call_later(
15 * 60, # Every 15 minutes
self._loop.create_task, self._periodic_check())
def stop_checking(self):
self._check_handler.cancel()
async def start_player(self):
await do something()
if not check_handler:
schedule_check()
async def stop_player(self):
await do something()
self.stop_checking()
async def _periodic_check(self):
await do_something()
self._schedule_check()
To pass a function (that needs some parameters) as a parameter to another function, that doesn't allow you to pass the parameters, you can bind the parameters using functools.partial.

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