* Master wait time metric
@ 2016-10-31 23:08 Sam Saffron
2016-10-31 23:36 ` Eric Wong
0 siblings, 1 reply; 3+ messages in thread
From: Sam Saffron @ 2016-10-31 23:08 UTC (permalink / raw)
To: unicorn-public
Hi Eric / everyone :)
I would like to start graphing how long our master process spends
waiting for worker processes to be available.
This metric will allow us to quickly tell if a unicorn is being
overloaded and allow us to quickly remediate.
Once a minute I want to ask the master process how long it spent
waiting for child processes to become available.
How would I go about getting that metric?
Sam
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: Master wait time metric
2016-10-31 23:08 Master wait time metric Sam Saffron
@ 2016-10-31 23:36 ` Eric Wong
2016-11-01 8:21 ` Sam Saffron
0 siblings, 1 reply; 3+ messages in thread
From: Eric Wong @ 2016-10-31 23:36 UTC (permalink / raw)
To: Sam Saffron; +Cc: unicorn-public
Sam Saffron <sam.saffron@gmail.com> wrote:
> Hi Eric / everyone :)
>
> I would like to start graphing how long our master process spends
> waiting for worker processes to be available.
Fwiw, the master doesn't wait for workers to become available for
processing requests. But I think I know what you mean to ask :>
Rather, the connection request sits in the listen queue (a kernel
object) shared by all workers, and instrumenting this is always
kernel-dependent (because unicorn avoids doing stuff in userspace).
> This metric will allow us to quickly tell if a unicorn is being
> overloaded and allow us to quickly remediate.
>
> Once a minute I want to ask the master process how long it spent
> waiting for child processes to become available.
>
> How would I go about getting that metric?
Linux-only, but you can probably look at Raindrops::LastDataRecv
https://bogomips.org/raindrops/Raindrops/LastDataRecv.html
Raindrops::Middleware can give you how big the listen queue is,
too. Ideally, this should never exceed 1.
https://bogomips.org/raindrops/Raindrops/Middleware.html
You can probably get the same metrics directly from the kernel
via systemtap, dtrace, or similar, too.
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: Master wait time metric
2016-10-31 23:36 ` Eric Wong
@ 2016-11-01 8:21 ` Sam Saffron
0 siblings, 0 replies; 3+ messages in thread
From: Sam Saffron @ 2016-11-01 8:21 UTC (permalink / raw)
To: Eric Wong; +Cc: unicorn-public
Brilliant, this will make it super easy to write a Prometheus
exporter, will post here once I am done.
On Tue, Nov 1, 2016 at 10:36 AM, Eric Wong <e@80x24.org> wrote:
> Sam Saffron <sam.saffron@gmail.com> wrote:
>> Hi Eric / everyone :)
>>
>> I would like to start graphing how long our master process spends
>> waiting for worker processes to be available.
>
> Fwiw, the master doesn't wait for workers to become available for
> processing requests. But I think I know what you mean to ask :>
>
> Rather, the connection request sits in the listen queue (a kernel
> object) shared by all workers, and instrumenting this is always
> kernel-dependent (because unicorn avoids doing stuff in userspace).
>
>> This metric will allow us to quickly tell if a unicorn is being
>> overloaded and allow us to quickly remediate.
>>
>> Once a minute I want to ask the master process how long it spent
>> waiting for child processes to become available.
>>
>> How would I go about getting that metric?
>
> Linux-only, but you can probably look at Raindrops::LastDataRecv
>
> https://bogomips.org/raindrops/Raindrops/LastDataRecv.html
>
> Raindrops::Middleware can give you how big the listen queue is,
> too. Ideally, this should never exceed 1.
>
> https://bogomips.org/raindrops/Raindrops/Middleware.html
>
>
> You can probably get the same metrics directly from the kernel
> via systemtap, dtrace, or similar, too.
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2016-11-01 8:21 UTC | newest]
Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
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2016-10-31 23:08 Master wait time metric Sam Saffron
2016-10-31 23:36 ` Eric Wong
2016-11-01 8:21 ` Sam Saffron
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