[Qgis-developer] qgis crash using QThread in a plugin script

Tue Sep 13 23:38:54 PDT 2016

2016-09-14 7:38 GMT+02:00 Akbar Gumbira <akbargumbira at gmail.com>:
Hi Akbar,

yes this is what I meant

    If you want to have a new fresh instance of your dialog every time you
open the dialog, you need to restructure your code.

I used Plugin Builder, I had not experience with it before, but how you
suggested the problem was that the dialog was instantiated in the __init__

    I think you use Plugin Builder and you instantiated the dialog in the
__init__ of the main file. You can remove the run method and just open the
dialog in the action.

I removed self.dlg = my_ui() from the __init__ and I put it in the run()
method and everithing works pretty well! Thank you very much! Could you
please answer
in Stackexchange so that everyone can see the solution? I will post later
the new code.

Marco, I didn't try yet what you posted in Stackexchange, I did not have
time till now but I found it well done, I will try it asap... so thanks for
your advice!

Best

s.

>
> On Wed, Sep 14, 2016 at 2:57 AM, Akbar Gumbira <akbargumbira at gmail.com>
> wrote:
>
>> Hi Sergio,
>>
>> It sounds like a new problem. Did removing the return fix the crash
>> problem that happened before? As your problem now that it prints double
>> letters, I am sure that you just need to clear some component's state
>> before running the worker.
>>
>> Do you have the plugin somewhere on github? If you have, I'll try it
>> myself
>>
>> Cheers
>>
>> On Sep 14, 2016 00:07, "Sergio Vignali" <vignalisergio30 at gmail.com>
>> wrote:
>>
>>> Hi Akbar,
>>>
>>> as you suggested I removed return but it didn't solve the problem...
>>> I don't get it because when I open the dialog the first time I can play
>>> with it changing word without problem
>>> (I mean that I can insert a new word several time and when I push apply
>>> everything works well).
>>> I think it's something that I should destroy when closing the dialog...
>>> but I don't find what!
>>> Two strange behaviours that I found is that sometimes after restarting
>>> the dialog if I insert the same word I inserted during the
>>> last run the plugin works well or if I change word it writes double
>>> items, like digiting "et" it inserts "ee" and "tt" and after it crashes,
>>> but how it gets
>>> the double letters in the loop?...
>>> It's for sure something related to the restarting as if I use the plugin
>>> reload it doesn't crash...
>>> Any idea? Anyway thanks for your suggestion!
>>>
>>> All the best
>>> s.
>>>
>>> 2016-09-10 10:42 GMT+02:00 Sergio Vignali <vignalisergio30 at gmail.com>:
>>>
>>>> Hi Akbar,
>>>> thank you for your answer, I'm abroad till Tuesday but I will test it
>>>> asap and let you know.
>>>> Best
>>>>
>>>> Il 09/set/2016 05:04, "Akbar Gumbira" <akbargumbira at gmail.com> ha
>>>> scritto:
>>>>
>>>>> Hi Sergio,
>>>>>
>>>>> DId you fix already your problems? I am not sure if my answer is 100%
>>>>> correct (so I don't post it in stackexchange) as  I didnt try it, but by
>>>>> judging your code:
>>>>>
>>>>> If I click apply without entering anything in the QLineEdit the
>>>>>> QgsMessageBar appears correctly but if I close the QDialog and I do the
>>>>>> same the QgisMessageBar has two items (1 more, see picture)
>>>>>
>>>>>
>>>>> Plugins initiallization happened when starting QGIS. So the plugin is
>>>>> already instantiated (along with your dialog, message bar, etc). Restarting
>>>>> (that is closing and opening again) the dialog in your code doesn't destroy
>>>>> all the instances. That is why the message bar has the previous messages.
>>>>> You can just clear the message bar once user opens the dialog.
>>>>>
>>>>> If I insert a word in the QLineEdit after opening the plugin for the
>>>>>> second time, clicking on apply Qgis crashes.
>>>>>
>>>>>
>>>>> This is not necessarily related to the crash :p:
>>>>>
>>>>>    -
>>>>>
>>>>>    word = unicode(self.dlg.inputedit.text())
>>>>>
>>>>>
>>>>> But QString is stored in unicode, no need to recast it
>>>>>
>>>>> For the cause of the crash, I strongly believe this is the problem:
>>>>>
>>>>>     def add_item(self, item):
>>>>>         self.list.addItem(item)
>>>>>         return
>>>>>
>>>>> Can you try to remove return there? I think it's forcing the thread to
>>>>> go back to the main loop (plugin Run method)
>>>>>
>>>>> Cheers
>>>>>
>>>>>
>>>>>
>>>>> On Wed, Sep 7, 2016 at 1:57 PM, Sergio Vignali <
>>>>> vignalisergio30 at gmail.com> wrote:
>>>>>
>>>>>> I posted my problem in gis.stackexchange, (
>>>>>> http://gis.stackexchange.com/questions/209602/qgis-crash-us
>>>>>> ing-qthread-in-a-plugin-script).
>>>>>> There you can find the full explanation of the problem and all the
>>>>>> code I used... It would be great to get some feedbacks!
>>>>>> Best
>>>>>> s.
>>>>>>
>>>>>> 2016-09-06 3:58 GMT+02:00 Akbar Gumbira <akbargumbira at gmail.com>:
>>>>>>
>>>>>>> It would be more helpful if you point to the code here. I had a
>>>>>>> problem with QThread (was initially inheriting QThread) but managed to fix
>>>>>>> the problem by creating workers and move the worker object to thread. This
>>>>>>> is a good article about multithreading in qgis
>>>>>>> https://snorfalorpagus.net/blog/2013/12/07/multithreading-in
>>>>>>> -qgis-python-plugins/
>>>>>>>
>>>>>>> On Sep 5, 2016 23:01, "Sergio Vignali" <vignalisergio30 at gmail.com>
>>>>>>> wrote:
>>>>>>>
>>>>>>>> Dear all,
>>>>>>>>
>>>>>>>> I wrote a python script that aims to execute neighbourhood
>>>>>>>> statistics in raster layer. My script uses QThread to update a QList and a
>>>>>>>> QProgressBar and everithing works fine if I run the script from PyCharm,
>>>>>>>> the progressbar and the list are updated. The problem appears when I move
>>>>>>>> my script in a Qgis plugin, the UI appears correctly but clicking OK the
>>>>>>>> software crashes...
>>>>>>>> I am using qgis 2.14 in a linux machine, do you have any advice?
>>>>>>>>
>>>>>>>> All the best
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>> --
>>>>>>>> Sergio Vignali
>>>>>>>>
>>>>>>>>
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>>>>>>>>
>>>>>>>
>>>>>>
>>>>>>
>>>>>> --
>>>>>> Sergio Vignali
>>>>>>
>>>>>>
>>>>>
>>>>>
>>>>> --
>>>>>
>>>>> *-------------------*
>>>>> *Akbar Gumbira *
>>>>> *www.akbargumbira.com <http://www.akbargumbira.com>*
>>>>>
>>>>
>>>
>>>
>>> --
>>> Sergio Vignali
>>>
>>>
>
>
> --
>
> *-------------------*
> *Akbar Gumbira *
> *www.akbargumbira.com <http://www.akbargumbira.com>*
>

-- 
Sergio Vignali
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