从虚拟机下载档案需要太多时间才能开始

Question

我用 Python 编写了一个从虚拟机下载 .tar.gz 存档的程序。下载工作正常，但问题是启动时间过长。这是我处理下载的代码部分：

import os
from wsgiref.util import request_uri
from wsgiref.simple_server import make_server

def download(self,dirr):
     file_url = os.environ['location'] + dirr
     headers = [('Content-Description', 'File Transfer'),
               ('Content-Type', 'application/octet-stream'),
               ('Content-Disposition', 'attachement; filename="'+os.path.basename(file_url)+'"'),
               ('Expires', '0'),
               ('Cache-Control', 'must-revalidate'),
               ('Pragma', 'public'),
               ('Content-Length', str(os.stat(file_url).st_size))]
        
      file_download = open(file_url, 'rb')
      return headers, file_download.read()

def server_app(environ, start_response):
    crt_handler = handler(request_uri(environ))
    headers, response_body = crt_handler.get() // this calls my download function, which is part of a class. 
    status = '200 OK'
    start_response(status, headers)
    return [response_body] 

def start_server():
   httpd = make_server("", PORT, server_app)
   httpd.serve_forever()

抱歉，如果我的代码中有些内容没有意义，我只粘贴了进行下载的部分。该程序做得更多。无论如何，有没有可能让下载开始更快？

Answer 1

file_download.read() 看起来不对。大多数 HTTP 库都支持从文件对象流式传输。

如果make_server 是wsgiref.simple_server.make_server，以下可能有效，但我无法测试。这个想法是不直接调用文件read，而是使用wsgiref.util.FileWrapper 将其转换为块的迭代器。然后从 app 函数中返回该迭代器。

def download(self,dirr):
     file_url = os.environ['location'] + dirr
     headers = [('Content-Description', 'File Transfer'),
               ('Content-Type', 'application/octet-stream'),
               ('Content-Disposition', 'attachement; filename="'+os.path.basename(file_url)+'"'),
               ('Expires', '0'),
               ('Cache-Control', 'must-revalidate'),
               ('Pragma', 'public'),
               ('Content-Length', str(os.stat(file_url).st_size))]

      file_download = open(file_url, 'rb')
      return headers, wsgiref.util.FileWrapper(file_download) # ***

def server_app(environ, start_response):
    crt_handler = handler(request_uri(environ))
    headers, response_body = crt_handler.get() // this calls my download function, which is part of a class. 
    status = '200 OK'
    start_response(status, headers)
    return response_body # ***

def start_server():
   httpd = make_server("", PORT, server_app)
   httpd.serve_forever()

注意上面有两个变化。标记为# ***