[quagga-dev 7641] Re: [PATCH] bgp: add snapshot to workaround slow commands

Chris Caputo ccaputo at alt.net
Thu Jan 14 19:27:29 GMT 2010


On Thu, 14 Jan 2010, Stephen Hemminger wrote:
> On Thu, 14 Jan 2010 17:34:53 +0000 (GMT) paul at jakma.org wrote:
> > On Wed, 13 Jan 2010, Stephen Hemminger wrote:
> > > On a fully loaded BGP instance, doing 'show ip bgp' can effectively
> > > kill the BGP process because the single BGP daemon thread is stuck waiting
> > > to feed information back to the vtysh.
> > 
> > > This patch is a simplistic solution to the problem. It adds:
> > >  show bgp snapshot
> > > which cause the original BGP daemon to fork. The vty client is then
> > > talking to the child which can then be used to do slow commands, and the
> > > parent BGP process is available to do normal duties.
> > 
> > That's simpler than all the infrastructure to wait on children in the 
> > parent and take back responsibility for the vty alright.
> > 
> > Thing is, how useful is this mode-change version? Usually the point 
> > at which I realise a command may take so long that it might hurt BGP 
> > is when waiting on a command to finish - after having executed it by 
> > definition.
> > 
> > I.e. this approach implies we should give up on the end-user 
> > transparent way. Can it not be gotten to work?
> 
> Yes, transparent is possible, just more difficult.

fork() on any display command that can take too much time?  (ie., "show ip 
bgp", "show ip bgp regexp", etc.)

Chris




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