Plain uWSGI error: uwsgi_response_write_body_do() TIMEOUT

requeststimeoutuwsgi

This looks like a well-known issue with Nginx+uWSGI timeouts, but my setup is different and I couldn't find information about it.

I run a Flask app on uWSGI, on http protocol (not sockets). When I query my API, sometimes I receive an error:

uwsgi_response_write_body_do() TIMEOUT !!!
IOError: : write error

I receive it more often during "business hour", i.e. not so often at night. I'm querying for long JSON data (geo coordinates, up to 50 MBytes) and sometimes I get no response at all, and sometimes I get part of the response. These are errors from Python's requests request:

requests.exceptions.ConnectionError: ('Connection aborted.', error(104, 'Connection reset by peer'))

requests.exceptions.ChunkedEncodingError: ('Connection broken: IncompleteRead(0 bytes read)', IncompleteRead(0 bytes read))

ValueError: Expecting object: line 1 column 5590371 (char 5590370)

ValueError: Unterminated string starting at: line 1 column 20998536 (char 20998535)

ValueError: end is out of bounds

# when I set `timeout=None` in Python
requests.exceptions.ReadTimeout: HTTPConnectionPool(host='mydomain.com', port=80): Read timed out. (read timeout=None)

The connection is over plain HTTP (no S). My uWSGI config below:

[uwsgi]
module = run:app
pidfile = /tmp/app.pid
logto = /var/log/uwsgi/%n.log

master = true
processes = 2

http-socket = 0.0.0.0:someport
http-timeout = 300

die-on-term = true

And I run this using uwsgi /path/to/inifile. There is no Nginx, but actually before, with Nginx, I was receiving same problems. So I ruled out this one.

How can I avoid these timeouts?

Best Answer

I also use nginx + uwsgi to produce a large file, and meet the same problem. I solved this problem by disable uwsgi temp-file buffer in nginx use directive uwsgi_max_temp_file_size 0;.

I think the transmission speed from nginx to client is far slower to the speed from uwsgi to nginx. And nginx's buffer is full, so uwsgi wait much time before there are space for nginx to receive new data and this make uwsgi's write request timeout.

I post a blog to analysis this problem in my blog.

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