[erlang-patches] release_handler_1 improvements

Fri Aug 26 10:08:40 CEST 2011

Hi again, Joe!

Sorry for being so slow - but I still don't really understand :(
My concerns are really about whether or not we should allow the upgrade to
be performed in this case. For sure I think we should

1) avoid the timeout, and
2) let the user know what the problem is

but is it correct to let the upgrade pass after this? Is it not an error
situation?

It seems to me that we risk getting into a situation where we believe that
the system is upgraded, but in fact there could be branches of the
supervisor tree where process have not had the chance to run their
code_change functions. I mean - even if we print the error report, there is
no guarantee that it is really detected unless the operation actually fails.

Please correct me if I completely misunderstood the situation.

Regards
/siri

2011/8/25 Joe Williams <joe@REDACTED>

>  Siri,
>
> I ran into two issues that this patch addresses. Check out the commit
> message at
> https://github.com/joewilliams/otp/commit/9c3a53789326cdd929f1c3b4525716b1c0abfe87 for
> the details. In both cases I found that in production an error in the logs
> was preferable to the restart of the VM since both are easily fixable with a
> small application change or in the case of the suspended supervisor using a
> different app up. Also see this comment in release_handler_1 regarding the
> supervisor,
> https://github.com/erlang/otp/blob/dev/lib/sasl/src/release_handler_1.erl#L454 which
> suggests this corner case is known by at least a few people. Currently there
> is no way to know *why* your VM just restarted after the upgrade in either
> case.
>
> Let me know if you have any other questions.
>
> -Joe
>
>
> --
> Name: Joseph A. Williams
> Email: joe@REDACTED
> Blog: http://www.joeandmotorboat.com/
> Twitter: http://twitter.com/williamsjoe
>
> On Thursday, August 25, 2011 at 6:35 AM, Siri Hansen wrote:
>
> Hi again, Joe!
>
> Could you please explain a bit about the situation where you discovered
> this problem? I agree that the timeout and VM restart is not very good, and
> it makes sense to check if the supervisor is suspended. But I'm not really
> sure if it is correct to allow the upgrade to continue when this error
> occurs. Even if an error message is printed, I guess it could be quite easy
> to miss this fact... and the question is if that would be a problem or not?
> Why is the supervisor suspended in the first place?
>
> Regards
> /siri
>
>
> 2011/8/25 Siri Hansen <erlangsiri@REDACTED>
>
> Hi Joe - I've just started looking at this. Do you think it would be
> possible to add a test case for it?
> Regards
> /siri
>
>
> 2011/8/24 Joe Williams <joe@REDACTED>
>
>  Anything I can do regarding this patch? I have happily been running it in
> production since I submitted it to the list in June.
>
> -Joe
>
>
> --
> Name: Joseph A. Williams
> Email: joe@REDACTED
> Blog: http://www.joeandmotorboat.com/
> Twitter: http://twitter.com/williamsjoe
>
> On Wednesday, July 6, 2011 at 3:43 PM, Joe Williams wrote:
>
>  Anything I can do to help this patch graduate?
>
> Thanks!
>
> -Joe
>
>
> --
> Name: Joseph A. Williams
> Email: joe@REDACTED
> Blog: http://www.joeandmotorboat.com/
> Twitter: http://twitter.com/williamsjoe
>
> On Tuesday, June 14, 2011 at 12:26 PM, Joe Williams wrote:
>
>  Updated this branch, please refetch.
>
> git fetch git://github.com/joewilliams/otp.git release_handler_1
>
>
> --
> Name: Joseph A. Williams
> Email: joe@REDACTED
> Blog: http://www.joeandmotorboat.com/
> Twitter: http://twitter.com/williamsjoe
>
> On Friday, June 10, 2011 at 8:52 AM, Joe Williams wrote:
>
>  Great, thanks!
>
>
> --
> Name: Joseph A. Williams
> Email: joe@REDACTED
> Blog: http://www.joeandmotorboat.com/
> Twitter: http://twitter.com/williamsjoe
>
> On Friday, June 10, 2011 at 8:51 AM, Raimo Niskanen wrote:
>
> On Thu, Jun 09, 2011 at 08:20:51AM -0700, Joe Williams wrote:
>
> Please fetch:
>
> git fetch git://github.com/joewilliams/otp.git release_handler_1
>
> This is a different branch with a better commit message and no white space
> changes.
>
>
> Excellent. I will include your patch in 'pu' after rewording the
> summary line to imperative form.
>
>
>
>
> --
> Name: Joseph A. Williams
> Email: joe@REDACTED
> Blog: http://www.joeandmotorboat.com/
> Twitter: http://twitter.com/williamsjoe
>
>
> On Thursday, June 9, 2011 at 7:44 AM, Joe Williams wrote:
>
> Nothing specific, just wondered if anyone had any thoughts on how I dealt
> with a couple of corner cases in installing releases.
>
> I'll fix things up and get back shortly.
>
> --
> Name: Joseph A. Williams
> Email: joe@REDACTED (mailto:joe@REDACTED <joe@REDACTED>)
> Blog: http://www.joeandmotorboat.com/
> Twitter: http://twitter.com/williamsjoe
>
>
> On Thursday, June 9, 2011 at 12:11 AM, Raimo Niskanen wrote:
>
> On Wed, Jun 08, 2011 at 03:41:37PM -0700, Joe Williams wrote:
>
> Any thoughts/feedback on this patch? I realize it doesn't follow the
> guidelines (https://github.com/erlang/otp/wiki/Submitting-patches) exactly
> and will clean it up soon.
>
>
> Anything in particular? I just got caught up in tideous merge work
> yesterday and missed to include your patch in 'pu', I was about
> to take it now.
>
> But if you have a cleanup I can wait for it...
>
>
>
> --
> Name: Joseph A. Williams
> Email: joe@REDACTED (mailto:joe@REDACTED <joe@REDACTED>)
> Blog: http://www.joeandmotorboat.com/
> Twitter: http://twitter.com/williamsjoe
>
>
> On Tuesday, June 7, 2011 at 2:33 PM, Joe Williams wrote:
>
> git fetch git://github.com/joewilliams/otp.git (
> http://github.com/joewilliams/otp.git) (
> http://github.com/joewilliams/otp.git) release_handler
>
>
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>
>
> --
>
> / Raimo Niskanen, Erlang/OTP, Ericsson AB
>
>
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>
> --
>
> / Raimo Niskanen, Erlang/OTP, Ericsson AB
>
>
>
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>
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