http://bugzilla.suse.com/show_bug.cgi?id=1074138 http://bugzilla.suse.com/show_bug.cgi?id=1074138#c1 Josef Reidinger <jreidinger@suse.com> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |amajer@suse.com, | |jreidinger@suse.com Flags| |needinfo?(amajer@suse.com) --- Comment #1 from Josef Reidinger <jreidinger@suse.com> --- Adam - it is possible that processing take this time or some other problem. Can you please attach yast logs? https://en.opensuse.org/openSUSE:Report_a_YaST_bug#I_reported_a_YaST2_bug.2C... -- You are receiving this mail because: You are on the CC list for the bug.

http://bugzilla.suse.com/show_bug.cgi?id=1074138 http://bugzilla.suse.com/show_bug.cgi?id=1074138#c5 --- Comment #5 from Adam Majer <amajer@suse.com> --- (In reply to Josef Reidinger from comment #4)

thanks, for logs and way to reproduce it. I reproduce it locally. From logs I see that problem is not solver, so it is problem with too many packages in UI, which need time to render.

Reason why second case is facter is that only few packages are listed, so it operates faster, but e.g. in my case the first case shows around 53 000 packages, which slows down UI.

And since Yast2 is using Qt, the only way this is slow is if you are using Qt wrong. Qt Model/View framework can very easily scale to millions of rows and be just as efficient as displaying 100 items. The only problem is using convenience classes that use QWidget based classes inside containers. Using 50,000+ QWidget based items will slow things down but I didn't look if this is what Yast2 is doing. -- You are receiving this mail because: You are on the CC list for the bug.

http://bugzilla.suse.com/show_bug.cgi?id=1074138 Stefan Hundhammer <shundhammer@suse.com> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |shundhammer@suse.com -- You are receiving this mail because: You are on the CC list for the bug.

http://bugzilla.suse.com/show_bug.cgi?id=1074138 http://bugzilla.suse.com/show_bug.cgi?id=1074138#c8 --- Comment #8 from Adam Majer <amajer@suse.com> --- In "modern" UI, like if you look at Thunderbird or Firefox or Chrome, when you want to find something, you have search-on-type feature. A snappy UI allows for something like that to actually be implemented. Listing all packages is useful, especially if I want to remove things I don't use and I don't know in which category things exist. In my case, it would be going down the list of all installed packages and seeing if I can uninstall things I don't use anymore. -- You are receiving this mail because: You are on the CC list for the bug.

http://bugzilla.suse.com/show_bug.cgi?id=1074138 http://bugzilla.suse.com/show_bug.cgi?id=1074138#c10 --- Comment #10 from Stefan Hundhammer <shundhammer@suse.com> --- (In reply to Adam Majer from comment #8)

In "modern" UI, like if you look at Thunderbird or Firefox or Chrome, when you want to find something, you have search-on-type feature. A snappy UI allows for something like that to actually be implemented.

We have a search filter view. Just use that one if you want to search something. We are not trying to recreate Thunderbird here (which has this kind of search box right above the list), and both Firefox and Chrome don't deal with lists at all; they have a generic "Find on this page" search function which is something completely different.

Listing all packages is useful, especially if I want to remove things I don't use and I don't know in which category things exist. In my case, it would be going down the list of all installed packages and seeing if I can uninstall things I don't use anymore.

Just use the "Installation Summary" filter view where you can select packages by status - e.g. "keep" in this example. Or use the "Repositories" filter view and select "@System". Both will give you a considerably shorter list that will not consume as many resources and slow down performance so drastically. I see no noticable delay when I do that with my 4399 installed packages. The only (easy) way to get all packages from all repositories is to go to the "RPM Groups" filter view and then select "ZZZ All". Guess why it's on the bottom of that tree: Because it is expected to slow down performance. As I wrote, I repeatedly defended that feature against requests to remove it because albeit it does have a cost in terms of performance and resource consumption, it is useful to some people in some cases. If this is now used against us, I strongly vote for removing it. Rewriting that entire part of the YQPackageManager because of that is just insane; and that's what this comes down to. As I wrote not so long ago in a thread on [research] that model-view part of the Qt item widgets is a royal PITA, it is poorly documented, it is very hard to test, it is hard to maintain. And for what? For a single-digit number of users who use the application the wrong way? Just use it the way it was meant to be used and be happy. See also https://mailman.suse.de/mlarch/SuSE/research/2017/research.2017.03/msg00035....

Re: [Research] Qt: How to hook into destruction of a widget? To: research@suse.de Subject: Re: [Research] Qt: How to hook into destruction of a widget? From: Stefan Hundhammer <shundhammer@suse.de> Date: Tue, 7 Mar 2017 11:47:12 +0100 In-reply-to: <c37738d9-2c8c-919b-47d3-df70946edf4a@suse.de> List-archive: <https://mailman.suse.de/mailman/private/research/>

On 07.03.2017 11:23, Adam Majer wrote:

...

I don't mean to be too picky here, just want to point out there are better ways of doing these things. QListView and relevant data model classes are **much** superior at this than using old-style QListWidget. Model/View separation has its many advantages.

After having gone through this with QDirStat and after having given 7 or 8 week-long Qt training courses each covering (almost) all aspects of Qt, I can only say:

No. Not only no, but HELL, NO.

Qt's model/view classes are made by theoretical people in their ivory tower for other theoretical people in their other ivory tower. They are a royal PITA, the documentation is (unlike all other Qt documentation) piss-poor, there are aspects of it that are completely (!) undocumented (talk about QPersistentModelIndex), and they are using private methods in their own derived classes all the time (which should have given them some hints that their own API is insufficient and too limiting), and it is completely undebuggable.

After working almost exclusively with and on Qt (we maintained the Qt libs for the Nokia Harmattan/MeegoTouch project on the N9 phone) I struggled with this stuff for QDirStat and just barely got it to work during the 12/2015 hackweek.

As a matter of fact, I had already officially given up QDirStat because of that just 2 hours prior to the 2015 SUSE Christmas party (already written a really interesting rant for its home page) because this crap just did random things with no means whatsoever to debug anything.

I didn't go to the party because I was so pissed off at that crap: I didn't want to spoil everybody else's party because of that. Only some hours later I got yet another idea how to track the problem down, and then I found what I had done wrong - without ANY of those Qt classes giving any hint whatsoever what they didn't like. I was just lucky.

Qt is otherwise a well-designed and great framework. But that model-view stuff is just a fucking piece of shit; I can't put it into other words.

So, for everybody just starting with Qt: By all means, forget that model-view stuff until you are comfortable with the easy way of doing things.

And when you start doing model-view stuff, try the easy one-dimensional list first, then work your way up to the two-dimensional table. Should you consider using the tree model, consider psychotherapy first to check what is wrong with you and what exactly you are trying to prove. Then talk to somebody who has done this before and ask him if he would really do it again.

For the purposes of average programming, use the QListWidget / QListWidgetItem classes rather than the QListView / QAbstractItemModel etc. classes. It's just too painful to use the latter with little (if any) gain whatsoever.

Kind regards -- Stefan Hundhammer <shundhammer@suse.de> YaST Developer / QDirStat Author Qt since 1998 / Certified Qt Developer / Qt Trainer

SUSE Linux GmbH GF: Felix Imendörffer, Jane Smithard, Graham Norton; HRB 21284 (AG Nürnberg) Maxfeldstr. 5, 90409 Nürnberg, Germany

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http://bugzilla.suse.com/show_bug.cgi?id=1074138 http://bugzilla.suse.com/show_bug.cgi?id=1074138#c12 --- Comment #12 from Stefan Hundhammer <shundhammer@suse.com> --- (In reply to Adam Majer from comment #11)

...

Our proposal for a workaround: Do not install those that you don't want.

That's a poor workaround. Another would be to just re-install the system?

If Debian is your preference where you cherry-pick everything you like and ignore everything else, maybe...

Somehow this works just fine in Aptitude on Debian with even more packages than Leap.

Aptitude is an NCurses (text-mode) utility, so this is beyond the point you previously made about Qt's model/view. OTOH Synaptic would be the Qt counerpart on Ubuntu (and Debian? not sure), and it doesn't have half (more exactly a quarter) of the features that our Qt package selector has. As a matter of fact, when I start that thing, it typically takes 10-20 seconds until it is finished building some index that always seems to be outdated. So, it seems to me you are clutching at straws, relying on others just not knowing that stuff. Also, how many packages exactly does Debian (or a recent Ubuntu) have that might possibly be displayed in any such "all packages" list? I could not find any numbers on the web.

But it doesn't work with Yast2 Qt GUI *or* console text UI.

That should give you some hints that it's not a problem of how that list is implemented in our YQPackageSelector, but that it's rather a problem of the sheer mass of packages that accumulated with all that splitting up large packages into tiny bits and pieces. Please remember that I do have a solid basis for comparison. When I started the data model in QDirStat, first I did it without sorting, and it was really fast, even with 400.000+ items in the tree. When I then introduced sorting with the thing that Qt recommends, the QSortFilterProxyModel, performance broke down completely because obviously it prefetched and sorted the complete tree in advance before showing *anything*. So I did that part myself (and this is when things get really hairy because the relevant Qt classes don't support you at all with this), and I only got snappy performance back because of deep internal knowledge of my data structures, lazy sorting and relying on not too many tree branches being open at the same time. But this would not work at all with such a package list. In effect, such a data model would have to keep a duplicate list of all the packages in the current view and sort it according to the current sort column. Not only does that mean duplicate at least all the pointers, it's also that old computer science problem of doing an efficient sorting; O(n*ln(n)) is the best you can achieve (e.g. with a heap sort which does not easily degrade in the pathological case). But one way or the other, you have to sort the complete list in the model to be able to create a QModelIndex which you need if you create your own model. And that's not much different than what the simplified QListWidget / QTableWidget (the convenience classes on top of QListView with a QAbstractListModel or QTableView with a QTableModel) do. And if you now write that you see poor performance with the same "show all" view in the NCurses version as well this just proves the point. So let's please stop this pointless discussion. We have too many packages now to handle them efficiently in such a "show all" list. So, if people insist that this is now too slow, the only real solution we have is not to offer that view anymore. Is that what you want? We ALWAYS offered that only with the caveat that there would be a heavy performance penalty. This is why we don't simply show that complete list be default upon startup, why it's somewhat hidden away. If you cannot accept that limitation, don't use it. The recommended way of all the use cases you mentioned is different for a good reason; I described it above in great detail. -- You are receiving this mail because: You are on the CC list for the bug.

http://bugzilla.suse.com/show_bug.cgi?id=1074138 http://bugzilla.suse.com/show_bug.cgi?id=1074138#c14 --- Comment #14 from Stefan Hundhammer <shundhammer@suse.com> --- Some of this may be related to the performance fix in https://github.com/libyui/libyui-qt-pkg/pull/82 . But some other things will remain unchanged by that PR. -- You are receiving this mail because: You are on the CC list for the bug.