<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"></head><body dir="auto">The important question here is not the connections in FIN_WAIT. It’s “why do you have so many sockets in ESTABLISHED state?”<div><br></div><div>First thing to do is to run </div><div>netstat -ant | grep tcp and see where these connections are to.</div><div><br></div><div>Do you have a configuration that is causing an endless loop of requests?<br><br><div id="AppleMailSignature" dir="ltr">Sent from my iPhone</div><div dir="ltr"><br>On Jan 9, 2019, at 9:57 PM, Anoop Alias <<a href="mailto:anoopalias01@gmail.com">anoopalias01@gmail.com</a>> wrote:<br><br></div><blockquote type="cite"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr">Hi,<div><br></div><div>Have had a really strange issue on a Nginx server configured as a reverse proxy wherein the server stops responding when the network connections in ESTABLISHED state and FIN_WAIT state in very high compared to normal working </div><div><br></div><div>If you see the below network graph, at around 00:30 hours there is a big spike in network connections in FIN_WAIT state, to around 12000 from the normal value of ~20</div><div><br></div><div><a href="https://i.imgur.com/wb6VMWo.png">https://i.imgur.com/wb6VMWo.png</a><br clear="all"><div><br></div><div>At this state, Nginx stops responding fully and does not work even after a full restart of the service.</div><div><br></div><div>Switching off Nginx and bring Apache service to the frontend (removing the reverse proxy) fix this and the connections drop</div><div><br></div><div>Nginx config & build setting</div><div>##################################</div><div><div> nginx -V</div><div>nginx version: nginx/1.15.8</div><div>built by gcc 4.8.5 20150623 (Red Hat 4.8.5-36) (GCC) </div><div>built with LibreSSL 2.8.3</div><div>TLS SNI support enabled</div><div>configure arguments: --prefix=/etc/nginx --sbin-path=/usr/sbin/nginx --modules-path=/etc/nginx/modules --with-pcre=./pcre-8.42 --with-pcre-jit --with-zlib=./zlib-1.2.11 --with-openssl=./libressl-2.8.3 --conf-path=/etc/nginx/nginx.conf --error-log-path=/var/log/nginx/error_log --http-log-path=/var/log/nginx/access_log --pid-path=/var/run/nginx.pid --lock-path=/var/run/nginx.lock --http-client-body-temp-path=/dev/shm/client_temp --http-proxy-temp-path=/dev/shm/proxy_temp --http-fastcgi-temp-path=/dev/shm/fastcgi_temp --http-uwsgi-temp-path=/dev/shm/uwsgi_temp --http-scgi-temp-path=/dev/shm/scgi_temp --user=nobody --group=nobody --with-http_ssl_module --with-http_realip_module --with-http_addition_module --with-http_sub_module --with-http_dav_module --with-http_flv_module --with-http_mp4_module --with-http_gunzip_module --with-http_gzip_static_module --with-http_random_index_module --with-http_secure_link_module --with-http_stub_status_module --with-http_auth_request_module --with-file-aio --with-threads --with-stream --with-stream_ssl_module --with-http_slice_module --with-compat --with-http_v2_module --add-dynamic-module=incubator-pagespeed-ngx-1.13.35.2-stable --add-dynamic-module=/usr/local/rvm/gems/ruby-2.5.3/gems/passenger-6.0.0/src/nginx_module --add-dynamic-module=ngx_brotli --add-dynamic-module=echo-nginx-module-0.61 --add-dynamic-module=headers-more-nginx-module-0.32 --add-dynamic-module=ngx_http_redis-0.3.8 --add-dynamic-module=redis2-nginx-module --add-dynamic-module=srcache-nginx-module-0.31 --add-dynamic-module=ngx_devel_kit-0.3.0 --add-dynamic-module=set-misc-nginx-module-0.31 --add-dynamic-module=ngx_http_geoip2_module --add-dynamic-module=testcookie-nginx-module --add-dynamic-module=ModSecurity-nginx --with-cc-opt='-O2 -g -pipe -Wall -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector-strong --param=ssp-buffer-size=4 -grecord-gcc-switches -m64 -mtune=generic' --with-ld-opt=-Wl,-E</div></div><div><br></div><div>#####################################</div><div><div># worker_processes auto; #Set to auto for a powerful server</div><div>worker_processes 1;</div><div>worker_rlimit_nofile 69152;</div><div>worker_shutdown_timeout 10s;</div><div># worker_cpu_affinity auto;</div><div>timer_resolution 1s;</div><div>thread_pool iopool threads=32 max_queue=65536;</div><div>pcre_jit on;</div><div>pid /var/run/nginx.pid;</div><div>error_log /var/log/nginx/error_log;</div><div><br></div><div>#Load Dynamic Modules</div><div>include /etc/nginx/modules.d/*.load;</div><div><br></div><div><br></div><div>events {</div><div>worker_connections 20480;</div><div>use epoll;</div><div>multi_accept on;</div><div>accept_mutex off;</div><div>}</div></div><div><br></div><div><div>lingering_close off;</div><div>limit_req zone=FLOODVHOST burst=200;</div><div>limit_req zone=FLOODPROTECT burst=200;</div><div>limit_conn PERSERVER 60;</div><div>client_header_timeout 5s;</div><div>client_body_timeout 5s;</div><div>send_timeout 5s;</div><div>keepalive_timeout 0;</div><div>http2_idle_timeout 20s;</div><div>http2_recv_timeout 20s;</div></div><div><br></div><div><br></div><div><div>aio threads=iopool;</div><div>aio_write on;</div><div>directio 64m;</div><div>output_buffers 2 512k;</div><div><br></div><div>tcp_nodelay on;</div><div><br></div><div>types_hash_max_size 4096;</div><div>server_tokens off;</div><div>client_max_body_size 2048m;</div><div>reset_timedout_connection on;</div><div><br></div><div>#Proxy</div><div>proxy_read_timeout 300;</div><div>proxy_send_timeout 300;</div><div>proxy_connect_timeout 30s;</div></div><div><br></div><div><div>#FastCGI</div><div>fastcgi_read_timeout 300;</div><div>fastcgi_send_timeout 300;</div><div>fastcgi_connect_timeout 30s;</div></div><div><br></div><div><div>#Proxy Buffer</div><div>proxy_buffering on;</div><div>proxy_buffer_size 128k;</div><div>proxy_buffers 8 128k;</div><div>proxy_busy_buffers_size 256k;</div><div><br></div><div>#FastCGI Buffer</div><div>fastcgi_buffer_size 128k;</div><div>fastcgi_buffers 8 128k;</div><div>fastcgi_busy_buffers_size 256k;</div></div><div><br></div><div><div>server_names_hash_max_size 2097152;</div><div>server_names_hash_bucket_size 128;</div></div><div>######################################################</div><div><br></div><div><br></div><div><br></div>-- <br><div dir="ltr" class="gmail_signature"><div dir="ltr"><div><b>Anoop P Alias</b> <div><br></div></div></div></div></div></div></div></div></div></div></div></div></div></div>
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