Nginx is not able to handle a large number of requests - nginx

Question

I have an scenario on where a nginx is in front of an Artifactory server.
Recently, while trying to pull a big number of docker images in a for loop, all at the same time (first test was with 200 images, second test with 120 images), access to Artifactory gets blocked, as nginx is busy processing all the requests and users will not be able to reach it.
My nginx server is running with 4 cpu cores and 8192 of ram.
I have tried to improve the handling of files in the server, by adding the bellow:
sendfile on;
sendfile_max_chunk 512k;
tcp_nopush on;
This made it a bit better (but of course, pull's of images with 1gb+ take much more time, due to the chunk size) - still, access to the UI would cause a lot of timeouts.
Is there something else that i can do to improve the nginx performance, whenever a bigger load is pushed thru it?
I think that my last option is to increase the size of the machine (more cpu's) aswell as the number of processes on nginx (8 to 16).
The full nginx.conf file follows bellow:
user www-data;
worker_processes 8;
pid /var/run/nginx.pid;
events {
worker_connections 19000;
}
http {
ssl_protocols TLSv1 TLSv1.1 TLSv1.2;
include /etc/nginx/mime.types;
default_type application/octet-stream;
gzip on;
gzip_disable "msie6";
sendfile on;
sendfile_max_chunk 512k;
tcp_nopush on;
set_real_ip_from 138.190.190.168;
real_ip_header X-Forwarded-For;
log_format custome '$remote_addr - $realip_remote_addr - $remote_user [$time_local] $request_time'
'"$request" $status $body_bytes_sent '
'"$http_referer" "$http_user_agent"';
server {
listen 80 default;
listen [::]:80 default;
server_name _;
return 301 https://$server_name$request_uri;
}
###########################################################
## this configuration was generated by JFrog Artifactory ##
###########################################################
## add ssl entries when https has been set in config
ssl_certificate /etc/ssl/certs/{{ hostname }}.cer;
ssl_certificate_key /etc/ssl/private/{{ hostname }}.key;
ssl_session_cache shared:SSL:1m;
ssl_prefer_server_ciphers on;
## server configuration
server {
listen 443 ssl;
server_name ~(?<repo>.+)\.{{ hostname }} {{ hostname }} _;
if ($http_x_forwarded_proto = '') {
set $http_x_forwarded_proto $scheme;
}
## Application specific logs
access_log /var/log/nginx/{{ hostname }}-access.log custome;
error_log /var/log/nginx/{{ hostname }}-error.log warn;
rewrite ^/$ /webapp/ redirect;
rewrite ^//?(/webapp)?$ /webapp/ redirect;
rewrite ^/(v1|v2)/(.*) /api/docker/$repo/$1/$2;
chunked_transfer_encoding on;
client_max_body_size 0;
location / {
proxy_read_timeout 900;
proxy_max_temp_file_size 10240m;
proxy_pass_header Server;
proxy_cookie_path ~*^/.* /;
proxy_pass http://{{ appserver }}:8081/artifactory/;
proxy_set_header X-Artifactory-Override-Base-Url $http_x_forwarded_proto://$host:$server_port;
proxy_set_header X-Forwarded-Port $server_port;
proxy_set_header X-Forwarded-Proto $http_x_forwarded_proto;
proxy_set_header Host $http_host;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
}
}
}
Thanks for the tips.
Cheers,
Ricardo