run_async, MessageHandler

[ciromanfredi]

Hi, I would like to know how to solve the following problem. I have a message manager that only activates for photos that arrive at the bot and performs some operations. When run_async = False then I don't have any kind of problem and even if I send multiple photos together everything works correctly, but when more photos arrive at the same time (and run_async = True) the operations are performed only for the first photo . I would like to know how I can handle this.

[Bibo-Joshi]

Hi. Tbh, that's not a lot of information to work with. Please

• keep in mind that sending photo albums equals sending multiple photos one by one. albums are just multiple messages nicely displayed
• read the ask-right page in the wiki ;)

[Bibo-Joshi]

Can you please provide a minimal working example that does what you want with run_async=False and fails with run_async=True? Take echobot.py from the examples folder as basis. Then we can have a better look at what's going wrong

[ciromanfredi]

I noticed that the moment I add the handler directly, run_async = True works fine. While in my case I am using a conversationHandler and the internal handlers of the conversationHandler are run_async = True but this gives me problems ... is it possible? I am attaching an example.

NOT WORK!!!!
def start(...):
    ...
    return BASE

def inphoto(...):
    ...
    ...
    return BASE

conv_handler = ConversationHandler(
entry_points=[CommandHandler('start', start)],
    states={
     BASE:[MessageHandler(Filters.photo,inphoto,run_async=True)]
    },
    fallbacks=[CommandHandler('stop', stop)],
    )

dispatcher.add_handler(conv_handler)
###################################################################################

WORK
dispatcher.add_handler(MessageHandler(Filters.photo,inphoto,run_async=True))

i want fix first case..

[Bibo-Joshi]

please read this https://telegra.ph/Minimal-Working-Example-for-PTB-07-18

[ciromanfredi]

Hi... the code is here... thank you for taking the time to solve the problem....
https://pastebin.com/5z65jiTE

[Bibo-Joshi]

All right, then the "problem" is that you use the run_async handler inside a ConversationHandler. When the first photo comes in, the CH hands the update over to a worker that runs your callback. Now the CH immediately picks up the next photo, but can only process it if the worker is done with the first picture. As that's not yet the case, CH discards the photo. with run_async=False, CH would wait for the worker to finish before picking up the next photo.

Note that you can

a) make your MassageHandler run with run_async=False and still make the revelant bot methods calls in inphoto run asynchronously (see the Performance Optimization wiki page for details
b) use the WAITING state of CH to specify what should happen if the CH receives an update while waiting for the worker to finish (you could i.e. tell the user to try again in a few seconds)