`start_kline_socket` callback does not permit writing to file

[mikkokotila]

Describe the bug The exact same code which works with start_trade_socket does not work with start_kline_socket in the sense that writing to fill does not work inside the callback function. Even just writing a dummy string does not work i.e. f.write() does nothing when it's inside the callback function.

To Reproduce

f = open('test.csv', 'a')

stream = ThreadedWebsocketManager(api_key=api_key, api_secret=api_secret)

stream.start()

def handle_socket_message(msg):
        f.write('test.csv')

stream.start_kline_socket(callback=handle_socket_message, symbol=symbol)

stream.join()

Expected behavior One should be able to run any arbitrary code, including writing to a file, inside the callback function.

Environment (please complete the following information):

• Python version: 3.8.12
• Virtual Env: conda
• OS: Mac (M1)
• python-binance version: 1.0.15

[halfelf]

Please flush the file stream.

[mikkokotila]

That did it. Thanks a lot!