How to solve nginx - no live upstreams while connecting to upstream client? : <p>Currently I am running a load test using JMeter on our system build on grails 3 running on tomcat. After sending 20k request per second I got “no live upstreams while connecting to upstream client” in nginx error log. Our application is multi-tenant base so I need to perform high load.  Here is my nginx configuration. </p>

<pre><code>worker_processes  16;
worker_rlimit_nofile 262144;
error_log  /var/log/nginx/error.log;

events {
    worker_connections  24576;
    use epoll;
    multi_accept on;
}


http {
    include       mime.types;
    default_type  application/octet-stream;

    sendfile        on;
    keepalive_timeout  600;
    keepalive_requests 100000;
    access_log off;
    server_names_hash_max_size  4096;
    underscores_in_headers  on;
    client_max_body_size 8192m;
    log_format vhost '$remote_addr - $remote_user [$time_local] $status "$request" $body_bytes_sent "$http_referer" "$http_user_agent" "http_x_forwarded_for"';

    proxy_connect_timeout      120;
    proxy_send_timeout         120;
    proxy_read_timeout         120;


    gzip  on;
    gzip_types text/plain application/xml text/css text/js text/xml application/x-javascript text/javascript application/json application/xml+rss image application/javascript;
    gzip_min_length  1000;
    gzip_static on;
    gzip_vary on;
    gzip_buffers 16 8k;
    gzip_comp_level 6;
    gzip_proxied any;
    gzip_disable "msie6";

    proxy_intercept_errors on;
    recursive_error_pages on;

    ssl_prefer_server_ciphers On;
    ssl_ciphers ECDHE-RSA-AES256-GCM-SHA384:ECDHE-RSA-AES256-SHA384:ECDHE-RSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-SHA256:ECDHE-RSA-RC4-SHA:ECDHE-RSA-AES256-SHA:RC4-SHA;
    include /etc/nginx/conf.d/*.conf;
}
</code></pre>

<p>How do I configure for high concurrent load?</p>
