Why so many old, unresolved bugs in Mapnik?

Posted by compdude on 23 June 2013 in English (English)

Hello, I have noticed that there are a large amount of Mapnik bugs that are several years old but are not resolved. What is up with this? Why haven't they been fixed??

I understand that there are a limited amount of people with programming experience, but seriously, it's crazy that we have bugs that are 4 (or more) years old. I know that you programmers have lives outside of OSM (at least I hope you do ;) ) but it doesn't make sense to have such old bugs in Mapnik. A lot of these bugs are things I really would like to see rendered and fixed in Mapnik.

I would love to help but I don't know much about programming and it would probably take me a year or more to learn whatever language is used in the Mapnik API. I would hope that these things would be changed by then...

So I would ask those programmers to look through the list of bugs and find the oldest ones and start fixing the most critical issues.

I also think that going forward, a standard should be set that a bug should not go more than 6 months (or a year tops) without being resolved.

Thanks in advance. Your work is very much appreciated.


PS: It isn't just mapnik that has super-old bugs; even Potlatch 2 has some 3 year-old bugs.

Comment from TomH on 23 June 2013 at 07:52

To clarify for other people reading this, the poster isn't really talking about bugs in mapnik, he's talking about bugs (really mostly enhancement requests) in the mapnik stylesheet used by OpenStreetMap for the default layer on the web site.

The simple answer as for there why so many is that nobody has volunteered to fix them - we're a volunteer project and we don't have a corp of paid cartographers.

The fact that the stylesheet is pretty much insanely hard to work with of course is one reason why people don't volunteer, which is why we are converting to carto format to try and reboot things - see the talk Firefishy mentioned for more information.

As to the idea of setting some kind of time limit, what exactly do you suggest we do when the the time runs out? Arbitrarily close the the bug? Send an armed posse to a random programmers house to force them to fix it?

Comment from iandees on 23 June 2013 at 12:39

I will volunteer for the OSM bug posse but I refuse to volunteer to fix stylesheet bugs.

Comment from compdude on 23 June 2013 at 20:17

Thanks for explaining that the stylesheet was so complicated. That would explain why nobody wants to fix these bugs. @firefishy, that video was really informative, and I'm glad Andy Allan is stepping up to simplify the stylesheet code. Hopefully that will allow more programmers to help and make it easier for people to learn how to work with the stylesheet.

About the time limit, I would hope that with the new programming language for the style sheet, we don't get unresolved bugs that are really old. I wouldn't want super-old bugs to be closed, perhaps the Trac website should have a feature where bugs older than 6 months would be outlined in red on the page that lists all the bugs, so that you can draw attention to programmers to encourage them to fix those bugs.

But, now that I know how complicated the stylesheet is, I will have more patience with you guys.

Comment from compdude on 23 June 2013 at 20:56

So when is Andy Allan's new creation going to be implemented in Mapnik?

Comment from Firefishy on 24 June 2013 at 05:30

It is already up at for testing. Once testing is done in a week or 3 it'll go live.

Comment from Pieren on 25 June 2013 at 12:23

And if you want to see the cartoCSS new style running for a while and evolving quickly, check out the osm-fr web site : Many changes have been done mainly by C.Quest contributor (zoom up to 19 with adapted style, sport leisures with playfield lines, and much more)

Comment from ab_fab on 25 June 2013 at 21:01

@Pieren: cquest style is visible at and zooms up to level 20 Stylesheet development can be followed on Github

Check also CartoCC tool, which helps for a collaborative development of MapCSS stylesheet with Tilemill

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