[Qgis-developer] Multi-threading rendering merged to master

Martin Dobias wonder.sk at gmail.com
Mon Feb 24 01:27:29 PST 2014

Hi Mathieu

On Mon, Feb 24, 2014 at 9:52 AM, Mathieu Pellerin <nirvn.asia at gmail.com> wrote:
> Martin,
> Fantastic work; I knew to expect a better rendering experience, yet I was
> caught by surprise at how much of a positive difference it makes.
> Few things from my 10-minutes play with it:
> * The map overview extend is broken, its extend goes way, way beyond the
> extend of the sum of all the layers in a given project

In my quick test everything seems to work fine, I will need more
details about the issue - feel free to file a bug report.

> * The 'xxx' option doesn't seem to be taken into consideration, the parallel
> rendering is always activated on my machine irrespective of whether I
> checked the box or not.

Works fine for me... but there are two different concepts:
1. rendering in background - GUI is responsive even while the map is
being rendered - this is always on
2. parallel vs sequential rendering - in sequential mode, there is
just one job that renders everything - in parallel mode, the job is
split into several jobs (one job per map layer) and jobs can therefore
use multiple cores

Are you sure you are not referring to point 1?
Also, it is worth noting that parallel rendering may bring
improvements only when there is more than one layer to render.

> * Half of the times I exited QGIS, the application process was not
> terminating and this error message was thrown: "*** Error in
> `/home/webmaster/apps/bin/qgis': corrupted double-linked list: 0x0a0680f0
> ***"; I had to manually kill the process

I had this problem too - due to some garbage in the build directory
(incompatible plugin DLLs). Try to run QGIS with --noplugins option.
But better do a clean build.


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