[QGIS-Developer] [processing] launching separate process/thread

[G. Allegri]

Side note: multiprocessing is part of the Python standard library.
https://docs.python.org/2.7/library/multiprocessing.html

Giovanni

Il 21 mag 2017 14:18, "Andreas Plesch" <andreasplesch at gmail.com> ha scritto:

> As a followup, here is the simple processing script which is my attempt at
> launching a separate task:
>
> https://github.com/andreasplesch/QGIS-X3D-Processing/blob/master/
> scripts/launch_webserver.py
>
> qgis2web does not seem to need a real http server for the preview as
> openlayers apparently can use the file protocol.
>
> -Andreas
>
> On Sat, May 20, 2017 at 5:29 PM, Andreas Plesch <andreasplesch at gmail.com>
> wrote:
>
>> I would like to launch a minimal web server from a processing script to
>> serve html properly (rather than using the file protocol).
>>
>> Since the web server needs to run and keep running separately from qgis
>> or the qgis python interpreter, I investigated various ways to accomplish
>> this using SimpleHTTPServer. On windows 2.18.7 as linux should be more
>> robust.
>>
>> - threading.Threat : start() works until the server actually serves a
>> file. Then qgis crashes with a minidump . For some reason, the crashing
>> happens not always but more often than not.
>> - multiprocessing : seems to be the recommended solution but I do not
>> seem to have it with Qgis python (?)
>> - QProcess.start() : works from the python terminal, seems robust but
>> does not seem to work from a processing script (?). Would be the preferred
>> solution.
>> - QProcess.startDetached('python',(args),dir) : works reliably but
>> requires killing and restarting the process to change the root directory
>> served
>>
>> This may all change with Qgis 3 but I suspect 2.18 will be around for a
>> while, too.
>>
>> Any recommendations or ideas would be welcome.
>>
>> I will look into qgis2web to see what it does.
>>
>> --
>> Andreas Plesch
>> 39 Barbara Rd.
>> Waltham, MA 02453
>>
>
>
>
> --
> Andreas Plesch
> 39 Barbara Rd.
> Waltham, MA 02453
>
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