学习Python进程池的使用，进程池带返回值

import multiprocessing


def func(msg):
    data1 = SQLTool().query("sql语句")

    return data1


@pcexpositionbp.route('/main')
def main():
    pool = multiprocessing.Pool(processes=4) # 创建4个进程
    results = []
    msg = "hello"
    results.append(pool.apply_async(func, (msg, )))
    pool.close() # 关闭进程池，表示不能再往进程池中添加进程，需要在join之前调用
    pool.join() # 等待进程池中的所有进程执行完毕
    print ("Sub-process(es) done.")

    # for res in results:
    #     print (res.get())
    #
    # print([x.get() for x  in results])
    return jsonify(data=[x.get() for x  in results][0])