pcp
[Top] [All Lists]

Re: [pcp] pmcd gives up on slow starting Perl PMDA

To: Ken McDonell <kenj@xxxxxxxxxxxxxxxx>
Subject: Re: [pcp] pmcd gives up on slow starting Perl PMDA
From: Nathan Scott <nathans@xxxxxxxxxx>
Date: Tue, 25 Mar 2014 17:39:23 -0400 (EDT)
Cc: pcp@xxxxxxxxxxx
Delivered-to: pcp@xxxxxxxxxxx
In-reply-to: <53300840.1070009@xxxxxxxxxxxxxxxx>
References: <532C975F.4020808@xxxxxxxxxxx> <532F56BC.9040500@xxxxxxxxxxxxxxxx> <146115274.4201680.1395623527453.JavaMail.zimbra@xxxxxxxxxx> <53300840.1070009@xxxxxxxxxxxxxxxx>
Reply-to: Nathan Scott <nathans@xxxxxxxxxx>
Thread-index: qgnCuOB3iVaqZ4Pj7uKsWEpuAuwHrA==
Thread-topic: pmcd gives up on slow starting Perl PMDA
Hi Ken,

----- Original Message -----
> Yep, that's the bones of the proposal for the "distracted" case.  But
> not necessarily for the startup case where pmcd would be none the wiser
> if it does not send a PDU to the PMDA before the PMDA is ready.
> 

OK.  That creds exchange happens immediately, as we discussed, so I
guess we'll need to document that we need to get through that early
protocol exchange before any long running transactions (IOW, Franks
observed pmdasystemd journald-API-takes-ridiculously-long-to-return
problem will not get fixed here).  I wonder if we should tweak/add
an API to allow a PMDA to enter the creds exchange earlier than it
normally would?

> If I can get the BUSY case to work, then I think we can generalize the
> pmdaControl method to provide the sort of semantics you're after here.
> 

Perfect.  I'm wondering too if, once we have this facility available,
we should reduce that default 5 second pmcd/pmda timeout to something
much shorter (1 second or less, even) to start weeding out any badly
behaving PMDAs and improve overall sampling accuracy?

cheers.

--
Nathan

<Prev in Thread] Current Thread [Next in Thread>