[FIXED] Python Asyncio - does not seem to be working in asynchronous mode

Issue

I have written below code but it does not seem to be giving the true asynchronous result.

code:

   async def getOHLC(kc, symbol):
        print("before .... " + symbol)
        ohlc_val = kc.ohlc(symbol)
        print(ohlc_val)
        print("after .... " + symbol)
    
    
    async def trackPrice(kc):
        stocks_array = []
        with open('../config/stocks.txt') as f:
            for line in f:
                stocks_array.append(line.rstrip('\n'))
    
        await asyncio.gather(*[getOHLC(kc, stock) for stock in stocks_array])
    
    if __name__ == "__main__":
        import time
        s = time.perf_counter()
        asyncio.run(trackPrice(connect()))
        elapsed = time.perf_counter() - s
        print(f"{__file__} executed in {elapsed:0.2f} seconds.")

Result:

 2020-12-13 21:37:21: Establishing connection ....
before .... NSE:TCS
{'NSE:TCS': {'instrument_token': 2953217, 'last_price': 2783.6, 'ohlc': {'open': 2792.7, 'high': 2807.7, 'low': 2764.55, 'close': 2784.3}}}
after .... NSE:TCS
before .... NSE:INFY
{'NSE:INFY': {'instrument_token': 408065, 'last_price': 1163.2, 'ohlc': {'open': 1159.7, 'high': 1171.95, 'low': 1155.25, 'close': 1167.75}}}
after .... NSE:INFY
before .... NSE:WIPRO
{'NSE:WIPRO': {'instrument_token': 969473, 'last_price': 353.5, 'ohlc': {'open': 357.4, 'high': 360, 'low': 352.65, 'close': 355.9}}}
after .... NSE:WIPRO
before .... NSE:ITC
{'NSE:ITC': {'instrument_token': 424961, 'last_price': 216.3, 'ohlc': {'open': 214.45, 'high': 217.95, 'low': 213.35, 'close': 212.7}}}
after .... NSE:ITC
before .... NSE:TINPLATE
{'NSE:TINPLATE': {'instrument_token': 894209, 'last_price': 145.25, 'ohlc': {'open': 146.3, 'high': 150.4, 'low': 143.6, 'close': 145.35}}}
after .... NSE:TINPLATE
before .... NSE:ALLCARGO
{'NSE:ALLCARGO': {'instrument_token': 3456257, 'last_price': 140.9, 'ohlc': {'open': 154, 'high': 155, 'low': 138, 'close': 139.1}}}
after .... NSE:ALLCARGO
before .... NSE:GDL
{'NSE:GDL': {'instrument_token': 3004161, 'last_price': 115.05, 'ohlc': {'open': 117, 'high': 118.4, 'low': 114.7, 'close': 114.85}}}
after .... NSE:GDL
before .... NSE:RELIANCE
{'NSE:RELIANCE': {'instrument_token': 738561, 'last_price': 2005.8, 'ohlc': {'open': 2013, 'high': 2038, 'low': 1974.25, 'close': 2007}}}
after .... NSE:RELIANCE
before .... NSE:TRF
{'NSE:TRF': {'instrument_token': 4604673, 'last_price': 112.5, 'ohlc': {'open': 112.9, 'high': 116.9, 'low': 110, 'close': 106.3}}}
after .... NSE:TRF
before .... NSE:PNCINFRA
{'NSE:PNCINFRA': {'instrument_token': 2402561, 'last_price': 179.5, 'ohlc': {'open': 189.7, 'high': 189.7, 'low': 177.85, 'close': 175.15}}}
after .... NSE:PNCINFRA
before .... NSE:DMART
{'NSE:DMART': {'instrument_token': 5097729, 'last_price': 2685.1, 'ohlc': {'open': 2647, 'high': 2715, 'low': 2632, 'close': 2622.05}}}
after .... NSE:DMART
before .... NSE:HEROMOTOCO
{'NSE:HEROMOTOCO': {'instrument_token': 345089, 'last_price': 3185.3, 'ohlc': {'open': 3200, 'high': 3239.5, 'low': 3169, 'close': 3194.3}}}
after .... NSE:HEROMOTOCO
before .... NSE:MAHLOG
{'NSE:MAHLOG': {'instrument_token': 98561, 'last_price': 406.1, 'ohlc': {'open': 405, 'high': 427.95, 'low': 402.1, 'close': 390.25}}}
after .... NSE:MAHLOG
before .... NSE:IRCON
{'NSE:IRCON': {'instrument_token': 1276417, 'last_price': 90.85, 'ohlc': {'open': 96, 'high': 96, 'low': 90, 'close': 88}}}
after .... NSE:IRCON
before .... NSE:VOLTAS
{'NSE:VOLTAS': {'instrument_token': 951809, 'last_price': 804.9, 'ohlc': {'open': 814, 'high': 820.9, 'low': 800.55, 'close': 814.25}}}
after .... NSE:VOLTAS
/Users/manjulamkumar/Desktop/myRepo/DEV/autoTrade/batch/access_token.py executed in 19.84 seconds.

can you please help me identify if I am missing something ? It is taking almost 20 seconds to fetch the data for 15 stocks. While I was expecting it to take max of 5 secs.

Solution

getOHLC method has no yield point (await something expression).

That's why asyncio has no chance to switch between coroutines.

Answered By - Andrew Svetlov