[Qgis-developer] MTR and Postgis - lots of crashes

Andreas Neumann a.neumann at carto.net
Thu Nov 6 02:17:42 PST 2014


Hi,

And how can I as a user control that the maximum should not be reached? 
Can I?

Andreas

On 06.11.2014 11:03, Denis Rouzaud wrote:
> QGIS allows 5 max I think
> So whenever QGIs reaches the max number of connections, it can't fetch 
> the requested layer but still waits for it...
>
> On 06.11.2014 11:01, Andreas Neumann wrote:
>> Hi Denis,
>>
>> Thanks for the hint.
>>
>> I had a check on the nr of open connections on our PostgreSQL server.
>>
>> The results of
>>
>> SELECT sum(numbackends) FROM pg_stat_database;
>>
>> are always in the 20ies.
>>
>> I allow 100 connections on the PostgreSQL server. So this does not 
>> explain the problems.
>>
>> The crashes always happen directly after project load. Once its 
>> loaded without a crash I never have subsequent crashes.
>>
>> So something critical seems to happen on project load.
>>
>> Andreas
>>
>>
>> On 06.11.2014 10:48, Denis Rouzaud wrote:
>>>
>>> On 06.11.2014 10:43, Andreas Neumann wrote:
>>>> Hi,
>>>>
>>>> Am I the only one that still gets a lot of crashes with complex 
>>>> projects when the data sources are on Postgis and MTR (parallel 
>>>> rendering in multiple cores) is turned on? I get most crashes on 
>>>> Windows, hardly any on Linux, but this may be due to the fact that 
>>>> Linux accesses Postgis locally, whereas the Win QGIS clients access 
>>>> Postgis remotely. Turning off MTR --> no more crashes.
>>>>
>>>> Is MTR and Postgis working flawlessly for everyone?
>>>>
>>>> These crashes really annoy me and I have to turn off MTR until 
>>>> these problems are fixed.
>>>>
>>>> Thank you for any hints / sharing your experiences with Postgis and 
>>>> MTR.
>>> I experienced freezes with MTR when I used joined attributes for 
>>> symbology/labelling. The joins being not cached.
>>> My interpretation was that the number of allowed connections to 
>>> postgres reached its maximum, and hence no connection is available 
>>> to fetch the layers used for labeling/symbology.
>>>
>>> Caching all my joins saved the problem on my side.
>>>
>>>
>>> I don't experience any trouble either on win or linux, and I suppose 
>>> I can say I have complex projects ;)
>>>
>>> Denis
>>>
>>>
>>
>



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