Error: Couldn't connect to server

Peter Booth peter_booth at me.com
Fri Apr 27 16:00:33 UTC 2018


I’m guessing that you have  script that keeps executing curl. What you can do is use curl -K ./fileWithListOfUrls.txt
and the one curl process will visit each url in turn reusing the socket (aka HTTP keep alive)

That said, curl isn’t a great workload simulator and, in the long time, you can get better results from something like wrk2


> On 27 Apr 2018, at 11:32 AM, mohan prakash via nginx <nginx at nginx.org> wrote:
> 
> Hi Liu
> 
> Client side I have increased the file descriptor value to 10000 , but still the same issue .
> 
> Also increased the FD in server side also then also same issue continuous.
> 
> 
> Followed below link to increase the FD limit.
> 
> Linux Increase The Maximum Number Of Open Files / File Descriptors (FD) - nixCraft <https://www.cyberciti.biz/faq/linux-increase-the-maximum-number-of-open-files/>
> 
> 
> Linux Increase The Maximum Number Of Open Files / File Descriptors (FD) ...
> How do I increase the maximum number of open files under CentOS Linux? How do I open more file descriptors under...
>  <https://www.cyberciti.biz/faq/linux-increase-the-maximum-number-of-open-files/>
> 
> 
> 
> 
> Regards
> Mohanaprakash T
> 
> 
> On Friday 27 April 2018, 7:06:51 PM IST, Liu Lantao <liulantao at gmail.com> wrote:
> 
> 
> It seems like your client has reach the limit of max open files. 
> 
> From the shell where you start you client program, run ‘ulimit -a’ to check the settings.
> You can also check the files open by your client in /proc/<pid>/fd/.
> 
> Increase that value is simple, you can change is temporarily or save to config file,
> there are tons of documents online about how to change it.
> On Fri, Apr 27, 2018 at 9:09 PM mohan prakash via nginx <nginx at nginx.org <mailto:nginx at nginx.org>> wrote:
> Hi Team
> 
> I am trying execute ~1000 curl request from my CentOS machine to my nginx server in ~5 sec.
> The same exercise continuous every ~5sec.
> 
> I am using libcurl to make the HTTP request.
> 
> During this process i see most of my request are failed with reason
> 
> Failure Curl Error Code[ 7 ] Reason[ Couldn't connect to server ]
> 
> Can someone suggest whether i am missing any configuration info in my nginx server. Below is my nginx server configuration
> 
> user nginx;
> worker_processes auto;
> error_log /var/log/nginx/error.log;
> pid /run/nginx.pid;
> 
> # Load dynamic modules. See /usr/share/nginx/README.dynamic.
> include /usr/share/nginx/modules/*.conf;
> 
> 
> worker_rlimit_nofile 262144;
> 
> events {
>     worker_connections 16384;
> }
> 
> http {
>     log_format  main  '$remote_addr - $remote_user [$time_local] "$request" '
>                       '$status $body_bytes_sent "$http_referer" '
>                       '"$http_user_agent" "$http_x_forwarded_for"';
> 
>     access_log  /var/log/nginx/access.log  main;
> 
>     sendfile            on;
>     tcp_nopush          on;
>     tcp_nodelay         on;
>     keepalive_timeout   65;
>     types_hash_max_size 2048;
> 
>     include             /etc/nginx/mime.types;
>     default_type        application/octet-stream;
> 
>     # Load modular configuration files from the /etc/nginx/conf.d directory.
>     # See http://nginx.org/en/docs/ngx_core_module.html#include <http://nginx.org/en/docs/ngx_core_module.html#include>
>     # for more information.
>     include /etc/nginx/conf.d/*.conf;
> 
>     limit_conn_zone $binary_remote_addr zone=perip:10m;
>     limit_conn_zone $server_name zone=perserver:10m;
> 
>     server {
>         limit_conn perip 2000;
>         limit_conn perserver 20000;
>         listen *:8080 backlog=16384;
>     }
> }
> 
> Regards
> Mohanaprakash T
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