[Tilesathome] WANTED: Tile viewing fastcgi written in C/C++

[spaetz]

On Wed, Jul 23, 2008 at 05:48:24PM +0100, Kai Krueger wrote:

> I could imagine that quite a few people upload through ADSL, which would 
> easily take 5 - 10 minutes on the more complex tilesets. I know that I 
> do. I could stop if it is seen as a problem though.

No, it's no problem in general. It's just that uploads take away precious slots for tile serving and as there is no easy way to restrict the number of uploads, there was no way of controlling the number of uploads.

> Some of the load on XAPI is probably caused by t at h clients? Does this 
> fallback make sense at the moment in this case? I feel that nearly 
> always when the main API has no data (i.e. times out), the same happens 
> to the XAPI. So it might only add extra load onto the XAPI without 
> gaining much? I don't have any numbers to back this up, so I don't 
> really know if this would help or harm.

I don't have numbers either, buut making OSMXAPI very busy when the t at h server is very busy can't help a lot.

> > I have now installed a lighthttp instance with 7 slots and all uploads will be redirected to using that. So from now on, uploads should not prevent us from doing tile serving. Let's see if this helps already.
> 
> Although this is a great idea in general and I think it makes complete 
> sense to split those two as well as possible, since then I can't upload 
> any tiles any more. I suspect it is caused by a stupid firewall that 
> blocks port 81 on our university network. Do more people have this problem?

I know, it's a quick and dirty fix. The proper solution would be a second IP address on the machine, and one can take care of the uploading and one could take care of the rest (for example). We'll need to keep it this way for a few days longer, I guess and I'll look into the options we have on that machine for limiting the number of upload slots without having to use non-standard ports.

> I had started writing an apache module in C for the tileset stuff before 
> I heard that Spaetz rewrote the entire server code. If it is helpful, I 
> would be happy to continue on it again and adapt it to the new server 
> layout. It would probably take a couple of days though till I find the 
> time to finish of the testing. Please let me know if other people are 
> working on it or if the memory consumption is no longer an issue to 
> prevent duplicate effort.

I have done a (not so) quick (my last C coding was years ago) and ugly fastcgi in ANSI C to serve tiles. And given that the t at h server has just died again, I will try to use it ASAP when the server is up again. 

spaetz