worker shutdown / reload (timer premature)

mat999 · 2016-05-10T20:14:05+00:00

On Tuesday, May 10, 2016 at 4:30:18 AM UTC-7, uuul...@gmail.com wrote:local body = ngx.arg[1]if re_match(body, '<!DOCTYPE html>', 'i')...

worker shutdown / reload (timer premature)

mat999

When nginx exits and a timer is scheduled, the timer is called with premature = true

Is it possible to manipulate or rely on this as a shutdown detection? Has anyone implemented a worker shutdown/reload hook?

lordnynex

Hello,

I do not recommend you rely on premature as an indication that the worker is exiting. It is possible for timers to execute prematurely outside of this situation.

You may be able to use it in conjunction with 'ngx.worker.exiting' https://github.com/openresty/lua-nginx-module#ngxworkerexiting to arrive at a more accurate conclusion.

Please be aware that ngx.worker.exiting can occur during HUP (reload), and is not necessarily an indication that the master will also be exiting. In the event of a HUP, your shared memory etc will be reset anyways so depending on your application I'd just assume permanent exit is imminent.

-Brandon

On Tue, May 10, 2016 at 5:14 AM, Mathew Heard <ma...@gmail.com> wrote:

When nginx exits and a timer is scheduled, the timer is called with premature = true

Is it possible to manipulate or rely on this as a shutdown detection? Has anyone implemented a worker shutdown/reload hook?

.

agentzh

Hello!

On Tue, May 10, 2016 at 5:14 AM, Mathew Heard wrote:
> When nginx exits and a timer is scheduled, the timer is called with
> premature = true
>
> Is it possible to manipulate or rely on this as a shutdown detection? Has
> anyone implemented a worker shutdown/reload hook?
>

Maybe one can rely on the following facts to detect different kinds of events:

1. Data in shdict survive HUP reload but not restart.
2. ngx.timer's handler's premature argument can be used as a indicator
of the current worker's (proper) shutdown. So can
ngx.worker.exiting().
3. init_by_lua* runs upon HUP reload or server (re)start only.
4. The relationshiop of ngx.worker.id() and ngx.worker.pid() may also
be helpful.

Regards,
-agentzh