synchronous restart

Clifton King cliftonk at gmail.com
Tue Aug 31 16:15:04 EDT 2010


Jamie,

Check to see that the new unicorn master process has a different PID
than the old one. You could have a script that sleeps for X seconds
and checks the PID after the deploy and if it matches the old one
alerts you with a tail of the stdout/stderr log files. I personally do
"ps aux | grep unicorn" a few times during the process if there are
any changes being deployed I'm wary of.

Clifton

On Tue, Aug 31, 2010 at 3:08 PM, Jamie Wilkinson <jamie at tramchase.com> wrote:
> On Aug 31, 2010, at 12:08 PM, Clifton King wrote:
>
>> If the new master process
>> fails at booting, you can tail the unicorn.stdout/err.log files to see
>> why.
>
>
> I should clarify... the above is exactly what I'm trying to avoid. i.e. how do you know if your new master failed to boot unless you are actively tailing the logs?
>
> It is extremely infrequent that our unicorns fail to start, but when it does we sometimes don't notice for quite some time. Our unicorns also restart so quickly that it is not an issue to do the restarts synchronously during deployment and trade speed for peace of mind
>
> I will probably just replace our basic `kill -USR2` with a small script that sends the signal and doesn't exit until the pidfile handover is complete. I'll be sure to share my results in case anyone else might find this useful.
>
>
> -jamie
>
> http://jamiedubs.com | http://fffff.at
>
>> On Tue, Aug 31, 2010 at 1:30 PM, Jamie Wilkinson <jamie at tramchase.com> wrote:
>>> Has anyone tried to synchronously restart their unicorns, to ensure that things restart OK?
>>>
>>> I imagine I could write a script that sent USR2 and then watched the log for a successful before exiting, but I dream there is something more MAGICAL
>>>
>>>
>>> Yours in mythical web servers,
>>>
>>> -jamie
>>>
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