I am creating a python code that does the following:
1 - creates an asynchronous function called "nums" than prints random numbers from 0 to 10 every 2 seconds.
2 - execute a function that prints "hello world" every 5 seconds.
3 - if the function "nums" prints 1 or 3, break the loop and end the program.
The thing is, it's not breaking out of the loop. What I am supposed to do? Thank you.
import asyncio
import random
async def nums():
while True:
x = print(random.randint(0, 10))
await asyncio.sleep(2)
if x == 1 or x == 3:
break
async def world():
while True:
print("hello world")
await asyncio.sleep(5)
async def main():
while True:
await asyncio.wait([nums(), world()])
if __name__ == '__main__':
asyncio.run(main())
You can use return_when=asyncio.FIRST_COMPLETED parameter in asyncio.wait:
import asyncio
import random
async def nums():
while True:
x = random.randint(0, 10)
print(x)
if x in {1, 3}
break
await asyncio.sleep(2)
async def world():
while True:
print("hello world")
await asyncio.sleep(5)
async def main():
task1 = asyncio.create_task(nums())
task2 = asyncio.create_task(world())
await asyncio.wait({task1, task2}, return_when=asyncio.FIRST_COMPLETED)
if __name__ == "__main__":
asyncio.run(main())
Prints (for example):
5
hello world
6
6
hello world
1
<program ends here>
Related
my code:
import asyncio
async def count(counter):
print(f"number of entries in the list {len(counter)}")
while True:
await asyncio.sleep(1 / 1000)
counter.append(1)
async def print_every_sec(counter):
while True:
await asyncio.sleep(1)
print(f"- 1 secund later. " f"number of entries in the list: {len(counter)}")
async def print_every_5_sec():
while True:
await asyncio.sleep(5)
print(f"---- 5 secund later")
async def print_every_10_sec():
while True:
await asyncio.sleep(10)
print(f"---------- 10 secund later")
async def main():
counter = list()
tasks = [
count(counter),
print_every_sec(counter),
print_every_5_sec(),
print_every_10_sec(),
]
await asyncio.gather(*tasks)
asyncio.run(main())
This is my conclusion but is not correct.
Correct conclusion around 1000 for each iteration.
I don't now what is it. This code works fine in online interpretations.
The assumption that asyncio.sleep(1 / 1000) (and to return control to other async routines) takes exactly one millisecond is not true.
Here's a more interesting example that records how long the sleep (and the time.perf_counter_ns() invocation) actually took:
import asyncio
import statistics
import time
max_count = 2500
async def count(counter):
while len(counter) < max_count:
t0 = time.perf_counter_ns()
await asyncio.sleep(1 / 1000)
t1 = time.perf_counter_ns()
counter.append((t1 - t0) / 1_000_000)
async def print_every_sec(counter):
while len(counter) < max_count:
await asyncio.sleep(1)
print(f'count: {len(counter)}; average: {statistics.mean(counter)} ms')
async def main():
counter = list()
tasks = [
count(counter),
print_every_sec(counter),
]
await asyncio.gather(*tasks)
asyncio.run(main())
On my Macbook, Python 3.9, etc, etc., the result is
count: 744; average: 1.341670
count: 1494; average: 1.33668
count: 2248; average: 1.33304
count: 2500; average: 1.325463428
so it takes 30% more than we expected to.
For sleeps of 10ms, the average is 11.84 ms. For sleeps of 100ms, the average is 102.9 ms.
I have an async method, as shown below.
I pass in lists of 1000 numbers, where the method will pass in each number to a helper function which will return something from a website.
I have a global variable called count, which i surround with locks to make sure it doesnt get changed by anything else
I use add_done_callback with the task to make this method async.
The goal is to keep sending a number in the list of 1000 numbers to the server, and only when the server returns data (can take anywhere from 0.1 to 2 seconds), to pause, write the data to a sql database, and then continue
The code works as expected without locks, or without making the callback function, (which is named 'function' below) asyncrounous. But adding locks gives me an error: RuntimeWarning: coroutine 'function' was never awaited self._context.run(self._callback, *self._args) RuntimeWarning: Enable tracemalloc to get the object allocation traceback
I am super new to async in python so any help/advice is greatly appriciated
My code is shown below. It is just a simple draft:
import time
import random
import asyncio
# from helper import get_message_from_server
async def get(number):
# get_message_from_server(number), which takes somewhere between 0.1 to 2 seconds
await asyncio.sleep(random.uniform(0.1, 2))
s = 'Done with number ' + number
return s
async def function(future, lock):
global count
print(future.result())
# write future.result() to db
acquired = await lock.acquire()
count -= 1 if (count > 1) else 0
lock.release()
async def main(numbers, lock):
global count
count = 0
for i, number in enumerate(numbers):
print('number:', number, 'count:', count)
acquired = await lock.acquire()
count += 1
lock.release()
task = asyncio.create_task(get(number))
task.add_done_callback(
lambda x: function(x, lock)
)
if (count == 50):
print('Reached 50')
await task
acquired = await lock.acquire()
count = 0
lock.release()
if (i == len(numbers) - 1):
await task
def make_numbers():
count = []
for i in range(1001):
count.append(str(i))
return count
if __name__ == '__main__':
numbers = make_numbers()
loop = asyncio.get_event_loop()
lock = asyncio.Lock()
try:
loop.run_until_complete(main(numbers, lock))
except Exception as e:
pass
finally:
loop.run_until_complete(loop.shutdown_asyncgens())
loop.stop()
The above comment helped a lot
This is what the final working code looks like:
import time
import random
import asyncio
from functools import partial
# from helper import get_message_from_server
async def get(number):
# get_message_from_server(number), which takes somewhere between 0.1 to 2 seconds
await asyncio.sleep(random.uniform(0.1, 2))
s = 'Done with number ' + number
return s
def function(result, lock):
print(result.result())
async def count_decrement(lock):
global count
print('in count decrement')
acquired = await lock.acquire()
count -= 1 if (count > 1) else 0
lock.release()
asyncio.create_task(count_decrement(lock))
async def main(numbers, lock):
global count
count = 0
for i, number in enumerate(numbers):
print('number:', number, 'count:', count)
acquired = await lock.acquire()
count += 1
lock.release()
task = asyncio.create_task(get(number))
task.add_done_callback(partial(function, lock = lock))
if (count == 50):
print('Reached 50')
await task
acquired = await lock.acquire()
count = 0
lock.release()
if (i == len(numbers) - 1):
await task
def make_numbers():
count = []
for i in range(1001):
count.append(str(i))
return count
if __name__ == '__main__':
numbers = make_numbers()
loop = asyncio.get_event_loop()
lock = asyncio.Lock()
try:
loop.run_until_complete(main(numbers, lock))
except Exception as e:
pass
finally:
loop.run_until_complete(loop.shutdown_asyncgens())
loop.stop()
I am currently making a discord bot, and I need it to make some loops in places but I also need it to be ready to respond to other people while it's in the loop.
Here's a simplified example:
n = 40
while n > 0:
print(n)
n -= 1
print('Hello')
Here I want the hello to be printed while the loop is happening, not after it finishes
You need to use Asyncio https://docs.python.org/3/library/asyncio.html
Here's an example that will print odd and even numbers at the "Same" time.
import asyncio, time
#prints out even numbers
async def func1():
evenNumbers = [num for num in range(50) if num % 2==0]
for num in evenNumbers:
await asyncio.sleep(1)
print(num)
#prints out odd numbers
async def func2():
oddNumbers = [num for num in range(50) if num % 2!=0]
for num in oddNumbers:
await asyncio.sleep(1)
print(num)
#handles asynchronous method calling
async def main():
await asyncio.gather(
func1(),
func2()
)
asyncio.run(main())
Feel free to try it out and see how it works.
I'm not sure for discord bot, but in general, you can use threading to do multiple things at the same time.
For example :
import threading
def thread_function():
n = 40
while n > 0:
print(n)
n -= 1
th = threading.Thread(target=thread_function)
th.start()
print('Hello')
I want to call two function concurrently in asyncio, I do it with loop.create_task, but I find that it is not concurrently actually.
Here is my code:
import asyncio
async def foo(v):
print(f"start {v}")
for i in range(5):
print(f"work in {v}")
print(f"done {v}")
def schedule_foo():
print("out start 1")
loop.create_task(foo(1))
print("out start 2")
loop.create_task(foo(2))
loop = asyncio.get_event_loop()
schedule_foo()
loop.run_forever()
this will output:
out start 1
out start 2
start 1
work in 1
work in 1
work in 1
work in 1
work in 1
done 1
start 2
work in 2
work in 2
work in 2
work in 2
work in 2
done 2
As you can see the main loop is async, but sub task is actually sync.
My question is how can I make the function run in concurrently actually?
You forgot to use await:
import asyncio
async def foo(v):
print(f"start {v}")
for i in range(5):
print(f"work in {v}")
await asyncio.sleep(0.1)
print(f"done {v}")
def schedule_foo():
print("out start 1")
loop.create_task(foo(1))
print("out start 2")
loop.create_task(foo(2))
loop = asyncio.get_event_loop()
schedule_foo()
loop.run_forever()
I am writing a minimalist code based on asyncio and composed of tasks, workers and a queue:
Workers look in the queue for a task and execute it
Tasks are represented as a random asyncio.sleep()
When a task is done it adds two more tasks to the queue
Two restrictions:
10 max worker at a time
100 tasks should be executed in total, the script should end then
To monitor the total number of tasks executed, I use a global variable task_queued updated each time a task is being added to the queue.
I'm sure there's a better, pythonic way, to do that and not using a global variable, but all the solution I came up with are much more complicated.
I'm missing something here, any clue ?
Here's my code:
import asyncio
from random import random
import sys
MAX_WORKERS = 10
MAX_TASKS = 100
task_queued = 0
async def task(queue, id="1"):
global task_queued
sleep_time = 0.5 + random()
print(' Begin task #{}'.format(id))
await asyncio.sleep(sleep_time)
if task_queued < MAX_TASKS:
await queue.put(id + ".1")
task_queued += 1
if task_queued < MAX_TASKS:
await queue.put(id + ".2")
task_queued += 1
print(' End task #{} ({} item(s) in the queue)'.format(id, queue.qsize()))
async def worker(worker_id, queue):
while True:
task_id = await queue.get()
print('Worker #{} takes charge of task {}'.format(worker_id, task_id))
await task(queue, task_id)
queue.task_done()
async def main():
global task_queued
print('Begin main \n')
queue = asyncio.Queue()
await queue.put("1") # We add one task to the queue
task_queued += 1
workers = [asyncio.create_task((worker(worker_id + 1, queue))) for worker_id in range(MAX_WORKERS)]
await queue.join()
print('Queue is empty, {} tasks completed'.format(task_queued))
for w in workers:
w.cancel()
print('\n End main')
if __name__ == '__main__':
loop = asyncio.get_event_loop()
try:
loop.run_until_complete(main())
except KeyboardInterrupt:
print('\nBye bye')
sys.exit(0)
Thank to user4815162342 for the answer, here's the code if anyone is interested
import asyncio
from random import random
import sys
class Factory:
"""
Factory
"""
def __init__(self, max_workers, max_tasks):
self.task_queued = 0
self.max_workers = max_workers
self.max_tasks = max_tasks
self.queue = asyncio.Queue()
async def task(self, task_id):
sleep_time = 0.5 + random()
print(' Begin task #{}'.format(task_id))
await asyncio.sleep(sleep_time)
if self.task_queued < self.max_tasks:
await self.queue.put(task_id + ".1")
self.task_queued += 1
if self.task_queued < self.max_tasks:
await self.queue.put(task_id + ".2")
self.task_queued += 1
print(' End task #{} ({} item(s) in the queue)'.format(task_id, self.queue.qsize()))
async def worker(self, worker_id):
while True:
task_id = await self.queue.get()
print('Worker #{} takes charge of task {}'.format(worker_id, task_id))
await self.task(task_id)
self.queue.task_done()
async def organize_work(self):
print('Begin work \n')
await self.queue.put("1") # We add one task to the queue to start
self.task_queued += 1
workers = [asyncio.create_task((self.worker(worker_id + 1))) for worker_id in range(self.max_workers)]
await self.queue.join()
print('Queue is empty, {} tasks completed'.format(self.task_queued))
for w in workers:
w.cancel()
print('\nEnd work')
if __name__ == '__main__':
loop = asyncio.get_event_loop()
factory = Factory(max_workers=3, max_tasks=50)
try:
loop.run_until_complete(factory.organize_work())
except KeyboardInterrupt:
print('\nBye bye')
sys.exit(0)