From: Jeff Garzik <jeff@garzik.org>
To: Pete Zaitcev <zaitcev@redhat.com>
Cc: Project Hail List <hail-devel@vger.kernel.org>
Subject: Re: [Patch 07/12] Chunk: retry initial CLD session open
Date: Sun, 18 Apr 2010 23:58:49 -0400 [thread overview]
Message-ID: <4BCBD4F9.10502@garzik.org> (raw)
In-Reply-To: <20100417224149.69ab366e@redhat.com>
On 04/18/2010 12:41 AM, Pete Zaitcev wrote:
> This was an error in the conversion to ncld. In the cldc code, we
> kick the state machine and the natural retries do the rest. Any
> failures occure there. But in ncld the original kick can fail too.
>
> Five retries give CLD server time to reboot. If it's down, then
> clients refuse to start. This may be a bad idea, or may be not.
> We may yet change the retries to be infinite, but for now it's
> better if builds terminate somehow in case of unexpected problems.
>
> Signed-off-by: Pete Zaitcev<zaitcev@redhat.com>
>
> ---
> server/cldu.c | 12 ++++++++++--
> 1 file changed, 10 insertions(+), 2 deletions(-)
>
> commit 44cdb98d2cceb2f4e081db2ee38ec60f1c1a8d8d
> Author: Master<zaitcev@lembas.zaitcev.lan>
> Date: Sat Apr 17 19:50:06 2010 -0600
>
> Retry the initial connection to the CLD server.
In the short term, this is acceptable.
In the medium term, this is a protocol detail that should be handled
somewhere in libcldc. We want all applications to behave the same way,
including the method by which they attempt to contact a master.
Because there could be multiple CLD servers, you cannot think of retries
in the context of a single server. This is crucial WRT work on #replica
branch, but it is also somewhat relevant to #master, because we might
have multiple servers listed in SRV records as fallbacks from which to
choose.
You don't want each application implementing this logic, because we want
to enforce some level of predictability in master-seeking behavior, and
in making decisions about when contacts attempts for -all- servers
should cease, as opposed to contact attempts for a -single- server. You
don't want it to take 30 minutes to try all servers in a cluster,
retrying a number of times on server A, then moving on to server B, etc.
Jeff
prev parent reply other threads:[~2010-04-19 3:58 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-04-18 4:41 [Patch 07/12] Chunk: retry initial CLD session open Pete Zaitcev
2010-04-19 3:58 ` Jeff Garzik [this message]
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