sudden nginx hang -- restart fails, "98: Address already in use"

[Jonathan Matthews]

On 5 February 2014 18:53, dwirth <nginx-forum at nginx.us> wrote:
> Hello, all.
>
> About an hour ago, out of the blue, my server stopped responding to webpage
> requests. We are using nginx + php-fpm on RHEL6.
>
> # service nginx status
> nginx (pid 31600) is running...
>
> # service nginx restart
> Stopping nginx:                                            [FAILED]
> Starting nginx: nginx: [emerg] bind() to 0.0.0.0:80 failed (98: Address
> already in use)
> nginx: [emerg] bind() to 0.0.0.0:443 failed (98: Address already in use)
> nginx: [emerg] bind() to 0.0.0.0:80 failed (98: Address already in use)
> nginx: [emerg] bind() to 0.0.0.0:443 failed (98: Address already in use)
> nginx: [emerg] bind() to 0.0.0.0:80 failed (98: Address already in use)
> nginx: [emerg] bind() to 0.0.0.0:443 failed (98: Address already in use)
> nginx: [emerg] bind() to 0.0.0.0:80 failed (98: Address already in use)
> nginx: [emerg] bind() to 0.0.0.0:443 failed (98: Address already in use)
> nginx: [emerg] bind() to 0.0.0.0:80 failed (98: Address already in use)
> nginx: [emerg] bind() to 0.0.0.0:443 failed (98: Address already in use)
> nginx: [emerg] still could not bind()
>
> I killed the process and was able to restart nginx so the immediate crisis
> is over, but I need to know: What the hell happened? What would cause nginx
> to hang like this? I have googled around and I see several discussions about
> what to do when this happens but zilch about how to keep it from happening.

The underlying cause I can't help with but, in this situation, I'd
always do a separate stop/stop so I could ensure the service had
stopped before starting it again. It hadn't here, and that's what
caused your "Address already in use" error messages.

J