nginx & uwsgi deploy django app get SIGPIPE 502 error - django

Question

I use nginx and uwsgi deploy my django webapp, the start few minutes all things well but after some time the ngnix will report 502 error and I check the uwsgi stderr log. there are some error marked => generated & SIGPIPE: writing to a closed pipe/socket/fd (probably the client disconnected) on request such as blow error message:
>[pid: 27427|app: 0|req: 1/1] 10.209.78.30 () {38 vars in 1030 bytes} [Mon Sep 29 15:46:00 2014] GET blabla...(just request url address) => generated 16018 bytes in 1428 msecs (HTTP/1.1 200) 6 headers in 157 bytes (1 switches on core 0)
Mon Sep 29 15:46:03 2014 - SIGPIPE: writing to a closed pipe/socket/fd (probably the client disconnected) on request blabla...(just request url address) (ip 10.209.78.30) !!!
Mon Sep 29 15:46:03 2014 - uwsgi_response_writev_headers_and_body_do(): Broken pipe [core/writer.c line 287] during GET blabla...(just request url address) (10.209.78.30)
IOError: write error
[pid: 27425|app: 0|req: 1/2] 10.209.78.30 () {38 vars in 2050 bytes} [Mon Sep 29 15:46:00 2014] GET blabla...(just request url address) => generated 0 bytes in 3578 msecs (HTTP/1.1 200) 6 headers in 0 bytes (0 switches on core 0)
Mon Sep 29 15:46:04 2014 - SIGPIPE: writing to a closed pipe/socket/fd (probably the client disconnected) on request blabla...(just request url address) (ip 10.217.95.130) !!!
Mon Sep 29 15:46:04 2014 - uwsgi_response_writev_headers_and_body_do(): Broken pipe [core/writer.c line 287] during GET blabla...(just request url address) (10.217.95.130)
IOError: write error
[pid: 27426|app: 0|req: 1/3] 10.217.95.130 () {38 vars in 1871 bytes} [Mon Sep 29 15:46:00 2014] GET blabla...(just request url address) => generated 0 bytes in 4415 msecs (HTTP/1.1 200) 6 headers in 0 bytes (0 switches on core 0)
Mon Sep 29 15:46:05 2014 - SIGPIPE: writing to a closed pipe/socket/fd (probably the client disconnected) on request blabla...(just request url address) (ip 10.217.95.130) !!!
Mon Sep 29 15:46:05 2014 - uwsgi_response_writev_headers_and_body_do(): Broken pipe [core/writer.c line 287] during GET blabla...(just request url address) (10.217.95.130)
IOError: write error
I replace the request url by blabla...
My nginx.conf is bleow:
location / {
add_header "Access-Control-Allow-Origin" "*";
add_header "Access-Control-Allow-Methods" "GET, OPTIONS";
add_header "Access-Control-Allow-Headers" "origin, authorization, accept";
uwsgi_pass unix:///tmp/djangoapp.sock;
include uwsgi_params;
}
uWSGI launch command:
uwsgi --socket /tmp/djangoapp.sock -p 10 --wsgi-file /opt/graphite/conf/graphite_wsgi.py --chmod-socket=666