Bug 590514 – sys-apps/portage: sub-optimal merge order triggered by PDEPEND and runtime dependency cycles

• Product: Portage Development
• Status: RESOLVED FIXED

[Description Zac Medico 2016-08-04 22:04:34 UTC]

There is a misbehavior in the depgraph._serialize_tasks method, where PDEPEND can cause the runtime cycle code to merge a very large runtime cycle and its dependencies, even though it would be more optimal to merge the dependencies first. In the main "while mygraph:" loop, the problem occurs when the prefer_asap flag is True, and there's a node in the asap_nodes list. The smallest_cycle variable ends up with a large runtime cycle along with some dependencies that are not involved in the cycle (which should therefore be merged earlier than the rest).

[Comment 1 Zac Medico 2016-08-04 22:18:28 UTC]

Some existing relevant code is visible in these commits, but apparently it doesn't always work as intended:

https://gitweb.gentoo.org/proj/portage.git/commit/?id=603569311daee6e2460051f46728a05cbae66880
https://gitweb.gentoo.org/proj/portage.git/commit/?id=075ce106b3ae1e55cc810b4c946deea83bcb4a8e

[Comment 2 Zac Medico 2016-08-05 02:16:53 UTC]

I have a working patch in the following branch:

https://github.com/zmedico/portage/tree/bug_590514

I'll submit it for review after I've added a test case.

[Comment 3 Zac Medico 2016-08-05 04:41:11 UTC]

Posted for review here:

https://archives.gentoo.org/gentoo-portage-dev/message/23fb8cfa5e8c8ad207c5e42e65024742
https://github.com/gentoo/portage/pull/39

[Comment 4 Zac Medico 2016-08-07 17:59:15 UTC]

This is in the master branch:

https://gitweb.gentoo.org/proj/portage.git/commit/?id=6412205462671735f6e8b3196a780bc4b0d6a077

[Comment 5 Zac Medico 2017-02-10 18:49:50 UTC]

Fixed in portage-2.3.3.