python多进程重复加载的解决方式

# autotrade/__init__.py
# __init__.py 定义全局的app路由
# 然后将其他模块由app装饰后的函数导入，flask即可识别所有的请求入口
import time
 
from flask import Flask
from multiprocessing import Process
 
# 配置全局app
 
# 导入index中定义的所有函数
# from autotrade.server.index import *
print("import will repeat")
def run_index():
  print("run_index once")
  app = Flask(__name__)
  # 启动web服务器，使用多线程方式，接收所有http请求
  app.run(host='0.0.0.0', port=5000, threaded=True,debug=False)
 
def run_orders():
  # 启动查询交易程序
  while True:
    print('执行相应的交易程序')
    time.sleep(3)
 
def main():
  # 主程序
  # 创建子进程
  jobs = []
  jobs.append(Process(target=run_index))
  # jobs.append(Process(target=run_orders))
  # 启动子进程
  for job in jobs:
    job.start()
 
  # 等待子进程结束返回
  for job in jobs:
    job.join()
 
if __name__ == '__main__':
  # run_index()
  main()

from flask_login import LoginManager
from flask_mail import Mail
from flask_socketio import SocketIO
from flask_migrate import Migrate
from flask_rq2 import RQ
from flask_wtf.csrf import CSRFProtect

from monitor.common.storage import LocalStorage, QiniuStorage, ObjectStorage
import config.global_var as gl_var
# from monitor.common.es_search import ESearchEngine

QINIU_AVAILABLE = gl_var.get_value("qiniu_available")
OSS_AVAILABLE = gl_var.get_value("oss_available")
REDIS_URI = gl_var.get_value("redis_uri")
BASEDIR = gl_var.get_value("basedir")
sbdwl = gl_var.get_value("sbdwl")


class Redis(object):

  def __init__(self):
    self._db = None

  def init_app(self, uri=REDIS_URI):
    self._db = _redis.Redis.from_url(uri)

  @property
  def db(self):
    return self._db

print("import foundation")

import threading
class Singleton(object):
  _instance_lock=threading.Lock()
  def __init__(self):
    pass
    # import time
    # print("sleep")
    # time.sleep(1)
  def __new__(cls, *args, **kwargs):
    if not hasattr(Singleton,"_instance"):
      with Singleton._instance_lock:
        if not hasattr(Singleton,"_instance"):
          print("create _instance----------------------------")
          Singleton._instance=object.__new__(cls,*args,**kwargs)

          app = Flask(__name__)
          Singleton._instance.db = SQLAlchemy(app)
          Singleton._instance.login_manager = LoginManager()