[Qgis-developer] QGIS Multi-threaded Rendering

Denis Rouzaud denis.rouzaud at gmail.com
Fri Jan 10 06:34:38 PST 2014

Hi Martin,

I noticed that QGIS crashes (with the multi-threaded rendering) when you 
turn editing mode on for a layer if this layer exists several times in 
the legend (i.e. the same layer is loaded several times with different 
styles or whatever).

I observed this at least for postgres.



On 07. 01. 14 22:23, Andreas Neumann wrote:
> Hi Martin,
> I tested it and can confirm that the PostgreSQL pooling works fine and
> fast now.
> I see more than 4 Postgis connections though. But maybe these
> connections are from other plugins using Postgis connections as well.
> Good to see progress!
> Thanks,
> Andreas
> Am 06.01.2014 13:31, schrieb Martin Dobias:
>> Hi Andreas
>> On Fri, Dec 13, 2013 at 8:31 PM, Andreas Neumann <a.neumann at carto.net> wrote:
>>> Hi Martin,
>>> I guess I am also running into the PostgreSQL issue. In general my
>>> PostgreSQL based projects with many layers freeze after a very short
>>> time, while the SpatiaLite based projects work very nicely.
>>> Too many PostgreSQL connections? Can we limit the PostgreSQL connections
>>> or can you better re-use existing connections?
>> A quick followup - today I have pushed some changes that introduce a
>> connection pool for PostgreSQL. This should remove the problem with
>> too many connections. It limits the maximum number of concurrent
>> connections from one QGIS instance to four. Also, when the connections
>> are not used for some time, they get closed to save resources (right
>> now it is after one minute).
>> Please test and let me know if things work better now.
>> I will probably also look at pooling of SpatiaLite connections - right
>> now the queries within SQLite are serialized, so within one SpatiaLite
>> database you will not see any performance gain with parallel
>> rendering.
>> Regards
>> Martin
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