I've come across an incredibly weird problem with POST responses using nginx 1.0.1 and uWSGI 0.9.7.2 on CentOS 5.6.

uWSGI successfully sends the response body to nginx, but nginx seems to ignore it if both (1) the request method is POST, and (2) the response length is less than 4052 bytes. The issue doesn't occur when serving directly using `uwsgi --http`, so I'm pretty sure the problem is something to do with nginx.

To explain things in code, this Python results in the desired response:

....def app_uwsgi(environ, start_response):
........start_response('200 OK', [('Content-type', 'text/html')])
........return [b'x' * 4052]

while this results in zero bytes being sent to the client for POST requests:

....def app_uwsgi(environ, start_response):
........start_response('200 OK', [('Content-type', 'text/html')])
........return [b'x' * 4051]

I stripped down to a minimal nginx.conf, and the issue still occurs:

....events {
........worker_connections 1024;
....}

....http {
........upstream uwsgi_connect {
............server 127.0.0.1:39275;
........}

........server {
............listen 20101;
............server_name domain.net;

............location / {
................uwsgi_pass uwsgi_connect;
................include uwsgi_params;
............}
........}
....}

Does anyone have any clue what could be causing this behavior?