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Re: understanding dpkg trigger cycles

[ CCed d-release. TL;DR: josch has created a list of packages that can
  generate trigger cycles (13), I'm filing bug reports. ]


On Thu, 2014-12-11 at 13:51:16 +0100, Johannes Schauer wrote:
> thanks a lot for your further explanations and clarifications!

Well, thanks a lot for doing the analysis!

> Based on this understanding I wrote a script which does the following:
>  1. calculate the set of packages A which declare an "interest" or
>     "interest-await" file trigger (no explicit triggers) in their
>     DEBIAN/triggers control file (Helmut supplied me with an initial list of
>     binary packages to check from the data on lilburn)
>  2. calculate the dependency closure of all packages in the set A
>  3. for each package in A, check if it gets triggered by any of the paths
>     provided by any of the packages in its dependency closure
> In summary, this finds some of the instances where a trigger cycle is created
> by an interested package directly or indirectly depending on a package which is
> put into triggers-awaited state for that particular package.
> Helmut helped me to limit the binary packages to search for DEBIAN/trigger
> files to 136 packages. After downloading and inspecting their content of
> DEBIAN/trigger, 48 packages remained which express an "interest" (without
> noawait) on a path.

(Sorry, I should have mentioned that I also had this information
available in lilburn. :/ )

> Out of those, it seems that 27 binary packages could potentially form a trigger
> cycle.

> The data is attached. The first column is the package containing the trigger.
> The second column is the path for which the trigger gets activated. The third
> column is a binary package that the binary package in the first column directly
> or indirectly depends on and which contains one or more files that trigger the
> package in the first column.
> Does this data look correct?

Yes, it does! I've excluded self-triggers though, as those are not
possible when path activated, because a package in an unpacked state
cannot accumulate pending triggers (sorry, should have mentioned that
before). Which gives a list of only 13 packages:


I'll start filing bug reports.

BTW, would it be possible to have this generated, say once a week? I
assume the major roadblock here is the need to get an up-to-date list
of trigger control files? We could export a list from lilburn for


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