[FIXED] asyncio: pass object trough loops and threads python

Issue

i'm just learning asyncio and threads, so if someting is wrong, sorry

this is my code:

async def callback_onlyAlert(update: Update, context):
    await update.message.reply_text('Ok! \nI will send you a message only when you can withdraw your USDN')
    #run alert 
    t = threading.Thread(target=middleware_alert, args=(update, context,))
    t.start()


def middleware_alert(update: Update,context):
    loop = asyncio.new_event_loop()
    asyncio.set_event_loop(loop)
    loop.run_until_complete(alert(update, context))
    loop.close()


async def alert(update: Update, context):
     global block
     global withdrawal_block
     while True:
        await  update.message.reply_text("⚠️⚠️ -10 MINUTES! ⚠️⚠️")
        time.sleep(20)

when i run it, i get got Future <Future pending> attached to a different loop error, i know that asyncio make a loop for the main thread, and you can't pass object trough loops, so i think that's why i get this error

anyway i get update and context outside that loop, when app starts, so i can't create it after the loop starts, there is any turnaround? or i'm doing something wrong? thanks

Solution

If all you're trying to do is launch the alert coroutine so that it runs at the same time as the rest of your code (without waiting for it to finish), I believe the asyncio-ish way to do that would be:

async def callback_onlyAlert(update: Update, context):
    await update.message.reply_text('Ok! \nI will send you a message only when you can withdraw your USDN')
    #run alert 
    asyncio.create_task(alert(update, context))

You shouldn't be running multiple event loops in different threads for this. Also, you should use await asyncio.sleep(10) instead of time.sleep(10), otherwise the entire event loop gets blocked.

Answered By - Oli