Upload big file on the server HTTP protocol

[Timych]

Now I am trying to learn some basics about cgi scripts (on Python). I want to implement saving a file on the server,when User send it (push the button in html form). I made it like in manual : http://cgi.tutorial.codepoint.net/big-file-upload

However when I send a large csv file ,which includes 100 000 rows, I get response that file is written successfully,but really few number of rows were written (around 30000) and the process seems to stop. What are the possible reasons?And how to deal with these files in future? Scrypt:

# -*- coding: utf-8 -*-
import cgi, os
import cgitb 

cgitb.enable()

try: # Windows needs stdio set for binary mode.
    import msvcrt
    msvcrt.setmode (0, os.O_BINARY) # stdin  = 0
    msvcrt.setmode (1, os.O_BINARY) # stdout = 1
except ImportError:
    pass

form = cgi.FieldStorage()

# Generator to buffer file chunks
def fbuffer(f, chunk_size=1024):
    while True:
        chunk = f.read(chunk_size)
        if not chunk: break
        yield chunk

# A nested FieldStorage instance holds the file
fileitem = form['file']

# Test if the file was uploaded
if fileitem.filename:


    fn = os.path.basename(fileitem.filename)
    f = open('C:/Users/timna/' + fn, 'wb')

    # Read the file in chunks
    for chunk in fbuffer(fileitem.file):
      f.write(chunk)
    f.close()

Server:

# -*- coding: utf-8 -*-
from http.server import HTTPServer, CGIHTTPRequestHandler
server_address = ("", 8000)
httpd = HTTPServer(server_address, CGIHTTPRequestHandler)
httpd.serve_forever()

Thanks for the response!

[snippsat]

Now I am trying to learn some basics about cgi scripts (on Python)

You should not

cgi is going to be deprecated in Python 3.8 and removed in 3.10

So the modern way to do CGI in Python is the use a smaller web-framework like Flask, Bottle, ect...
Python community has written WSGI(all Python code) to replace CGI(had a lot of problems that could not be fixed).

So eg Flask is layer above WSGI to make all easier connect to web with HTML/CSS than using WGSI directly.
Uploading Files | Flask file upload.