[Melbourne-pm] Monitoring Starman apps

Toby Corkindale toby.corkindale at strategicdata.com.au
Wed Mar 14 22:23:37 PDT 2012

On 15/03/12 13:26, Toby Corkindale wrote:
> On 15/03/12 13:00, Matt Sharpe wrote:
>> I was talking to Miyagawa about this and he mentioned
>> Plack::Middleware::ServerStatus(::Lite); it does essentially what
>> Apache's mod_status does and returns info on workers and active
>> requests. Maybe something to look at? The Lite edition should do what
>> you want if I understood your initial post correctly…
> That looks like what I'm after!
> It doesn't take into account io wait and keepalive sessions,
> unfortunately, but as long as there's a reverse proxy in front, those
> shouldn't be occurring, I think.

Just an update..
I've had a look at Plack::Middleware::ServerStatus::Lite and one of its 
dependencies, Parallel::Scoreboard.

I'm not very confident in them after looking at the source. The 
scoreboard module looks like it could suffer from race conditions.
(And some of the code to try and avoid update collisions looks.. 
interesting. Not in a good way.)

The serverstatus module shells out to capture output from 'ps' via a 
regex and then compares it to the scoreboard, rather than being able to 
rely on it, which seems odd to me.. why isn't its own info reliable? I 
suspect the scoreboard never gets cleaned up when workers die :/

Still, it's a start.


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