uWSGI keepalive

Question

Is it possible somehow to pass through the keepalive limitation of uwsgi? If not, what is the best way of persistent connection implementation. I'm using NGiNX + uWSGI (Python), and I want clients to have asynchronous updates from server.

Answer 1

UWSGI supports keep-alive via --http-keepalive option if you receive requests via http.

/tmp$ cat app.py
def application(env, start_response):
    content = b"Hello World"
    start_response('200 OK', [
        ('Content-Type','text/html'),
        ('Content-Length', str(len(content))),
    ])
    return [content]

Run with:

/tmp$ uwsgi --http=:8000 --http-keepalive -w app &> /dev/null

And we can see connect calls via strace:

~$ strace -econnect wrk -d 10 -t 1 -c 1 http://127.0.0.1:8000 
connect(3, {sa_family=AF_INET, sin_port=htons(8000), sin_addr=inet_addr("127.0.0.1")}, 16) = 0
Running 10s test @ http://127.0.0.1:8000
  1 threads and 1 connections
  Thread Stats   Avg      Stdev     Max   +/- Stdev
    Latency    92.32us   56.14us   2.81ms   97.20%
    Req/Sec    11.10k   389.34    11.84k    68.32%
  111505 requests in 10.10s, 7.98MB read
Requests/sec:  11040.50
Transfer/sec:    808.63KB
+++ exited with 0 +++

See? Only one connection.