[Qgis-developer] [Qgis-user] Problem with "add postgis layers" in qgis 1.80

[Martin Dobias]

On Fri, Jul 20, 2012 at 11:59 AM, Jürgen E. <jef at norbit.de> wrote:
> Hi Etienne,
>
> On Thu, 19. Jul 2012 at 19:16:03 -0300, Etienne Tourigny wrote:
>> I guess then the pragmatic way to resolve these kinds of issues is to spawn
>> them in working threads and implement mechanisms for cancelling it.  Is this
>> possible with the current api?
>
> I don't think so - the providers probably don't like being called from several
> threads at once - or lack an interface to try that to begin with (see threading
> branch...)

When there are simultaneous requests to read some data, there are two
options what to do:
1. serialize the reads: the second request will be blocked until the
first finishes
2. do the reads at once in separate connections to the resource
(database / file / ...)

The threading branch used the first approach, so the threads would be
served one-by-one. In future the providers could be improved to
support the latter approach - that that will need further work.


Martin