python - (502 Bad Gateway) Handle load on uwsgi_server + flask + nginx -

we serving flask using uwsgi. seems work fine till tried load test on site.

on increased load site went down , started giving 502 - bad gateway.

errors:

2017/08/17 15:22:57 [error] 1209#1209: *2394 connect() unix:/home/ubuntu/opt/myproject/app/myproject.sock failed (11: resource temporarily unavailable) while connecting upstream, client: ip_address_here, server: ads.myproject.co, request: "get /app_wall?aff_id=2&google_aid=&ios_ifa_md5=&ios_ifa=&mac_address=&device_id=&device_os_version=4.1&device_os=android&device_model=gt-i9082&device_brand=samsung&country_code=mu&city=port louis&referer=&user_agent=dalvik%2f1.6.0+%28linux%3b+u%3b+android+4.1.2%3b+gt-i9082+build%2fjzo54k%29&ip=105.235.159.208&datetime=2017-08-17+15%3a22%3a57&affiliate_sub5=15343&affiliate_sub4=&affiliate_sub3=&affiliate_sub2=56292544&affiliate_sub1=6ac48ae370ec4e30b942aac4c7d1e127&affiliate_source=1252_15343&creative_url_id=0&host_offer_id=325771&transaction_id=102a553241d652c43754314686378d&mobile_carrier=%3f&region_code=pu http/1.1", upstream: "uwsgi://unix:/home/ubuntu/opt/myproject/app/myproject.sock:", host: "nativeads.mobilepad.co" 2017/08/17 15:25:19 [error] 1212#1212: *2525 upstream timed out (110: connection timed out) while reading response header upstream, client: xxx.yyy.zz.aza, server: ads.myproject.co, request: "get /app_wall?params=params http/1.1", upstream: "uwsgi://unix:/home/ubuntu/opt/myproject/app/myproject.sock", host: "nativeads.mobilepad.co" 2017/08/17 15:25:36 [error] 1212#1212: *2530 upstream timed out (110: connection timed out) while reading response header upstream, client: ipaddress_here, server: sync.myproject.co.uk, request: "get /login/ http/1.1", upstream: "uwsgi://unix:/home/ubuntu/opt/myproject/app/myproject.sock", host: "sync.myproject.co.uk" 

following details of our architecture: (sorry long details)

nginx (/etc/nginx/sites-available/file.conf) :

# upstream component nginx needs connect upstream flask {     server unix:///home/ubuntu/opt/app/myproject.sock fail_timeout=0; # file socket }  # configuration of server server {     server_name sync.myproject.co.uk;     listen         80;      client_max_body_size 2000m;     proxy_read_timeout 6000;      location / {         include     uwsgi_params;         uwsgi_pass  unix:/home/ubuntu/opt/myproject/app/myproject.sock;     }  }  server {     server_name ads.myproject.co;     listen         80;      client_max_body_size 2000m;     location / {         return http://myproject.co.uk;     }      location ~ ^/(some_endpoint|someendpoint)/*{         include     uwsgi_params;         uwsgi_pass  unix:/home/ubuntu/opt/myproject/app/myproject.sock;     }      location /static/ {         include     uwsgi_params;         uwsgi_pass  unix:/home/ubuntu/opt/myproject/app/myproject.sock;     }      error_page 404 = @foobar;     location @foobar {         return 301 http://myproject.co.uk;     } }  server {     server_name cdn.myproject.co.uk;     listen         80;      client_max_body_size 2000m;     location / {         include     uwsgi_params;         uwsgi_pass  unix:/home/ubuntu/opt/myproject/app/myproject.sock;     }  } 

project.ini

[uwsgi] module = wsgi   master = true processes = 16  socket = myproject.sock chmod-socket = 660 vacuum = true  die-on-term = true  env = production_environment=true logto = logs/%n.log enable-threads = true 

please let me know if anymore details needed.

i not able understand problem nginx, flask app or aws instance size application hosted. using m4.2xlarge instance of now.

also if tell me how check count of number of requests/sec give stats too.

p.s: have tried increasing server instance size m4.4xlarge same issue.