On Wed, 29 Jan 2014 16:33:04 +0100 Sebastian Luther <sebastianlut...@gmx.de> wrote:
> Hi all, > > as you may have noticed, emerge can in some cases take ages ( >5-10 > minutes) to resolve dependencies these days. This happens when lots > of backtracking is required to solve slot conflicts and/or to > schedule slot operator rebuilds. The problem is that the current > backtracking implementation has to rebuild the entire dependency > graph from scratch each time it backtracks. > > This series of patches is a first step into fixing this problem. > > What these patches do: > Patch 1 > ------- > Adds a new data structure called package_tracker. This data > structure is meant to replace several of the depgraph data structures. > It has some new features not present in the existing data > structures. 1) It can properly deal with several packages in the same > slot. 2) It supports removal of previously added packages. > 3) It tracks package conflicts automatically. > 4) It has a more general concept of conflicts. > > Not all of the features are used for now, but they will make > future changes easier. > > Patch 2-5 > --------- > These patches replace the old data structures with the > package tracker > > Patch 6-8 > --------- > These patches fix several issues with emerge output. 6 and 8 > are somewhat independent of the other patches in this series. Patch 7 > introduces a new function used in Patch 10. > > Patch 9 > ------- > New function for patch 10. > > Patch 10 > -------- > This patch builds on top of all the previous patches. It > introduces two new functions to the depgraph class. A function to > remove packages that have previously been pulled in and a function to > solve simple slot conflicts without backtracking. > > This should resolve most "no parents that aren't satisfied by > other packages in this slot" slot conflicts. > > You may find these patches on github here: > https://github.com/few/fews-portage-branch/tree/package_tracker > > Some numbers > ------------ > > My system has quite a number of conflicts that give emerge a hard time > resolving dependencies. > > -uDN world > > Without the patches: > * 11 unsolved slot conflicts > * 2 unsolved blockers > * takes 5 backtracking steps and then fails > > With the patches: > * no unsolved slot conflicts or blockers > * takes 7 backtracking steps and then succeeds > > In this case it actually became slower, but was finally able to find > a solution. > > -e world > > Without the patches: > * 5 unsolved slot conflicts > * 1 unsolved blocker > * takes 23 backtracking steps and then fails > > With the patches: > * 1 unsolved slot conflict (From a quick look it looks like > there really is no solution.) > * takes 13 backtracking steps and then fails > > In this case it's a lot faster, but still unacceptably slow. > The result is improved by solving 4 out of 5 conflicts. > > > I'm replying to all the series. I saw no glaring obvious mistakes. This code is in areas I know little about, but your changes do seem logical. Your additional fixes to these patches also look good. If Mike/Arfrever gives the thumbs up. They're good to go in my opinion. -- Brian Dolbec <dolsen>
