Flask+SQLite+Tornado 在 Windows 2019 下 100 并发都撑不住是怎么回事？

非常简易的一个测试程序

# -*- coding: UTF-8 -*-

from flask import Flask, request
import json
import time
import re

import sys
import asyncio

from tornado.ioloop import IOLoop
from tornado.wsgi import WSGIContainer
from tornado.httpserver import HTTPServer

import sqlalchemy
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy import Column, Integer, String, create_engine
from sqlalchemy.orm import sessionmaker

engine = create_engine('sqlite:///database.db?check_same_thread=False')

Base = declarative_base()


class ClientLog(Base):
    __tablename__ = 'clientlog'
    log_id = Column(Integer, primary_key=True, autoincrement=True)
    message = Column(String(512))

    def __repr__(self):
        return "A"


from sqlalchemy.ext.declarative import DeclarativeMeta


class AlchemyEncoder(json.JSONEncoder):
    def default(self, obj):
        if isinstance(obj.__class__, DeclarativeMeta):
            # an SQLAlchemy class
            fields = {}
            for field in [x for x in dir(obj) if not x.startswith('_') and x != 'metadata']:
                data = obj.__getattribute__(field)
                try:
                    json.dumps(data)  # this will fail on non-encodable values, like other classes
                    fields[field] = data
                except TypeError:
                    fields[field] = None
            # a json-encodable dict
            return fields

        return json.JSONEncoder.default(self, obj)


Base.metadata.create_all(engine, checkfirst=True)

Session = sessionmaker(bind=engine)
session = Session()


app = Flask("app")

@app.route('/api', methods=['GET', 'POST'])
@app.route('/api/', methods=['GET', 'POST'])
def api1():
    session.add(ClientLog(message="test"))
    session.commit()
    return "test"

def launch_server():
    if sys.platform == 'win32':
        asyncio.set_event_loop_policy(asyncio.WindowsSelectorEventLoopPolicy())
    http_server = HTTPServer(WSGIContainer(app))
    http_server.listen(8080)
    IOLoop.current().start()

launch_server()

在阿里云的 Windows 2019 模板下 100 并发就会崩溃退出，报错

Exception in thread Tornado selector:
Traceback (most recent call last):
  File "C:\Users\Administrator\AppData\Local\Programs\Python\Python311\Lib\threading.py", line 1045, in _bootstrap_inner
    self.run()
  File "C:\Users\Administrator\AppData\Local\Programs\Python\Python311\Lib\threading.py", line 982, in run
    self._target(*self._args, **self._kwargs)
  File "C:\Users\Administrator\AppData\Local\Programs\Python\Python311\Lib\site-packages\tornado\platform\asyncio.py", line 574, in _run_select
    rs, ws, xs = select.select(to_read, to_write, to_write)
                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
ValueError: too many file descriptors in select() 

但是我在 Windows 10 的电脑上测试并发没问题 之前测试换了另外一个对 Windows 更友好的 web framework （想不起来名字，找了半天没找到）可以是可以，但是估计它用了不止一个进程写 SQLite ，导致冲突无法提交更改 业务需求调用一个 Windows Only 的 pip 包 ，无法更换 Linux 服务器