Re: Fwd: Client still connect failed leader after that mon down

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On Mon, 21 Dec 2015, Zhi Zhang wrote:
> Regards,
> Zhi Zhang (David)
> Contact: zhang.david2011@xxxxxxxxx
>               zhangz.david@xxxxxxxxxxx
> 
> 
> 
> ---------- Forwarded message ----------
> From: Jaze Lee <jazeltq@xxxxxxxxx>
> Date: Mon, Dec 21, 2015 at 4:08 PM
> Subject: Re: Client still connect failed leader after that mon down
> To: Zhi Zhang <zhang.david2011@xxxxxxxxx>
> 
> 
> Hello,
> I am terrible sorry.
> I think we may not need to reconstruct the monclient.{h,cc}, we find
> the parameter is mon_client_hunt_interval is very usefull.
> When we set mon_client_hunt_interval = 0.5? the time to run a ceph
> command is very small even it first connects the down leader mon.
> 
> The first time i ask the question was because we find the parameter
> from official site
> http://docs.ceph.com/docs/master/rados/configuration/mon-config-ref/.
> It is write in this
> 
> mon client hung interval

Yep, that's a typo. Do you mind submitting a patch to fix it?

Thanks!
sage


> 
> Description:The client will try a new monitor every N seconds until it
> establishes a connection.
> Type:Double
> Default:3.0
> 
> And we set it. it is not work.
> 
> I think may be it is a slip of pen?
> The right configuration parameter should be mon client hunt interval
> 
> Can someone please help me to fix this in official site?
> 
> Thanks a lot.
> 
> 
> 
> 2015-12-21 14:00 GMT+08:00 Jaze Lee <jazeltq@xxxxxxxxx>:
> > right now we use simple msg, and cpeh version is 0.80...
> >
> > 2015-12-21 10:55 GMT+08:00 Zhi Zhang <zhang.david2011@xxxxxxxxx>:
> >> Which msg type and ceph version are you using?
> >>
> >> Once we used 0.94.1 with async msg, we encountered similar issue.
> >> Client was trying to connect a down monitor when it was just started
> >> and this connection would hung there. This is because previous async
> >> msg used blocking connection mode.
> >>
> >> After we back ported non-blocking mode of async msg from higher ceph
> >> version, we haven't encountered such issue yet.
> >>
> >>
> >> Regards,
> >> Zhi Zhang (David)
> >> Contact: zhang.david2011@xxxxxxxxx
> >>               zhangz.david@xxxxxxxxxxx
> >>
> >>
> >> On Fri, Dec 18, 2015 at 11:41 AM, Jevon Qiao <scaleqiao@xxxxxxxxx> wrote:
> >>> On 17/12/15 21:27, Sage Weil wrote:
> >>>>
> >>>> On Thu, 17 Dec 2015, Jaze Lee wrote:
> >>>>>
> >>>>> Hello cephers:
> >>>>>      In our test, there are three monitors. We find client run ceph
> >>>>> command will slow when the leader mon is down. Even after long time, a
> >>>>> client run ceph command will also slow in first time.
> >>>>> >From strace, we find that the client first to connect the leader, then
> >>>>> after 3s, it connect the second.
> >>>>> After some search we find that the quorum is not change, the leader is
> >>>>> still the down monitor.
> >>>>> Is that normal?  Or is there something i miss?
> >>>>
> >>>> It's normal.  Even when the quorum does change, the client doesn't
> >>>> know that.  It should be contacting a random mon on startup, though, so I
> >>>> would expect the 3s delay 1/3 of the time.
> >>>
> >>> That's because client randomly picks up a mon from Monmap. But what we
> >>> observed is that when a mon is down no change is made to monmap(neither the
> >>> epoch nor the members). Is it the culprit for this phenomenon?
> >>>
> >>> Thanks,
> >>> Jevon
> >>>
> >>>> A long-standing low-priority feature request is to have the client contact
> >>>> 2 mons in parallel so that it can still connect quickly if one is down.
> >>>> It's requires some non-trivial work in mon/MonClient.{cc,h} though and I
> >>>> don't think anyone has looked at it seriously.
> >>>>
> >>>> sage
> >>>>
> >>>> --
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> >>>
> >>>
> >>> --
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> >
> >
> >
> > --
> > ????
> 
> 
> 
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