Short delays in sending TCP streams can cause HTTP parsing issues

[abersheeran]

All need is a simple HTTP demo to receive POST requests. Then use the following Python code to send a request to reproduce the problem:

import socket
import time

sock = socket.socket()
sock.connect(('cloudscan-service', 80))
print(sock.send(b'POST /cloud3 HTTP/1.1\r\nHost: cloudscan-service\r\nAccept: */*\r\nAccept-Encoding: gzip, deflate\r\nConnection: keep-alive\r\nUser-Agent: python-httpx/0.25.0\r\nContent-Length: 19\r\nContent-Type: application/json\r\n\r\n'))
time.sleep(0.0005)
print(sock.send(b'{"type": "avlinfo"}'))
print(sock.recv(1024))

The script will get

204
19
b''

But if we remove this short sleep, everything will return to normal.

import socket

sock = socket.socket()
sock.connect(('cloudscan-service', 80))
print(sock.send(b'POST /cloud3 HTTP/1.1\r\nHost: cloudscan-service\r\nAccept: */*\r\nAccept-Encoding: gzip, deflate\r\nConnection: keep-alive\r\nUser-Agent: python-httpx/0.25.0\r\nContent-Length: 19\r\nContent-Type: application/json\r\n\r\n'))
print(sock.send(b'{"type": "avlinfo"}'))
print(sock.recv(1024))

The script will get

204
19
b'HTTP/1.1 200 OK\r\nContent-Length: 155\r\nConnection: Keep-Alive\r\n\r\n{"authexpdate":"","authmaxcount":0,"avlcount":46218278,"avlexpdate":"20250731","avlversion":"2022022801","dbblackcount":0,"dbversion":"","dbwhitecount":0}\n'

Has anyone encountered similar problems? I'm a newbie in C++ and don't know how to solve this problem.

[an-tao]

Is the server written by Drogon?

[abersheeran]

Yes.

[an-tao]

I'll check it out later

[an-tao]

I can't reproduce this issue, what operating system is your server running on?

[abersheeran]

Thank you for your quick response. We have reached the following conclusions after testing in different environments.

The Drogon service runs in the k8s pod, and other services access it through its corresponding service, and the above results will be obtained.
There are no problems when the Drogon service and test scripts are run on our development machine (physical machine).

All programs run on ubuntu18.04 system under x86 architecture.

[an-tao]

I don't have a Kubernetes environment, but when I test the server running in Docker, everything works fine. You can try capturing packets on your Kubernetes node to see if all request data is being delivered.