Flask路由中使用Kaleido调用Plotly的pio.write_image导出图片时程序挂起

我有一个Flask应用，需要展示图片，同时还要用pio.write_image将图片本地存储。在普通Python脚本（helperz.py）里测试这段逻辑是完全正常的：

if __name__ == "__main__":
    ic("name=main in strategies_helperz")
    print(plotly.__version__, kaleido.__version__)
    # create data
    data_original = generate_dummy_data(symbol="BTCUSDT", num_records=100)

    # transform to dataframe
    df = klines_to_dataframe(data_original)

    fig = plot_ohlc(df=df, exchange="mexc")

    user="ZEoJt367"
    src_path = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
    current_time = datetime.now().strftime("%Y%m%d_%H%M%S")
    folder_path = os.path.join(src_path, "screenshots", user)
    if not os.path.exists(folder_path):
        ic(f'{folder_path} not existing, should create one!')
        os.makedirs(folder_path)

    fileName = os.path.join(folder_path, current_time + str(".png"))    
    saveScreenshot(fig=fig, fileName=fileName, width=800, height=500)

下面是saveScreenshot函数的实现：

def saveScreenshot(fig, fileName, width=800, height=500):
    ic(f"def saveScreenshot to ${fileName}")
    try:
        pio.write_image(fig=fig, file=fileName, width=width, height=height, engine="kaleido")
        ic(f"image saved to ${fileName} !")
        return True
    except Exception as e:
        ic(f"Error saving image: {e}")

但如果在Flask的路由中使用这段逻辑（app.py文件，在文件层级上比helperz.py高一级），程序会直接挂起：

@app.route('/api/klines_for_plotly/<string:exchange>/<string:symbol>/<string:timeframe>', methods=['POST'])
def apiKlinesForPlotly(exchange, symbol, timeframe):
    ic(f"def apiKlinesForPlotly - POST - for ${exchange}, symbol: ${symbol}, timeframe: ${timeframe}")
  
    klines_with_names=[]

    if exchange == "mexc":
        klines_mexc=getKlinesDataMexc(symbol=symbol, interval=timeframe)
        for data in klines_mexc:
            kline = Mexc_KLine(data)
            klines_with_names.append(kline)

    elif exchange == "binance":
        klines_binance=getKlinesDataBinance(symbol=symbol, interval=timeframe)
        for data in klines_binance:
            kline = Binance_KLine(data)
            klines_with_names.append(kline)

    # transforming klines_with_names to pandas df
    df=klinesWithNamesToDf(klines_with_names=klines_with_names)
   
    # creating a plotly fig based on df
    fig = plot_ohlc(df=df, exchange=exchange)

    user="ZEoJt367"
    src_path = os.path.dirname(os.path.abspath(__file__))
    current_time = datetime.now().strftime("%Y%m%d_%H%M%S")
    folder_path = os.path.join(src_path, "screenshots", user)
    if not os.path.exists(folder_path):
        ic(f'{folder_path} not existing, should create one!')
        os.makedirs(folder_path)

    fileName = os.path.join(folder_path, current_time + str(".png"))
    fig = plot_ohlc(df=df, exchange=exchange)
    saveScreenshot(fig=fig, fileName=fileName, width=800, height=500)
    fig_json = fig.to_json()

    return fig_json

在这个场景下saveScreenshot永远不会执行完成。我已经按照很多类似问题的建议安装了旧版本的Kaleido，但还是没有解决问题。会不会是因为在Flask路由中使用时，这个函数需要改成异步的？

备注：内容来源于stack exchange，提问作者Gregor Soto拧ek