[GRASS-dev] [GRASS GIS] #3799: Python 3 Error using MultiModule and ParallelModuleQueue

[GRASS GIS]

#3799: Python 3 Error using MultiModule and ParallelModuleQueue
-------------------------+-------------------------
 Reporter:  AnikaBettge  |      Owner:  grass-dev@…
     Type:  defect       |     Status:  new
 Priority:  normal       |  Milestone:  7.6.1
Component:  Default      |    Version:  svn-trunk
 Keywords:  python3      |        CPU:  Unspecified
 Platform:  Linux        |
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 I tested the examples on
 https://grass.osgeo.org/grass77/manuals/libpython/pygrass.modules.interface.html?highlight=parallelmodulequeue#pygrass.modules.interface.module.ParallelModuleQueue
 with Python 3.6.7.

 The example "Check MultiModule approach with three by two processes
 running in a background process" leads to


 {{{
 ...

 Traceback (most recent call last):
   File "/usr/lib/python3.6/multiprocessing/queues.py", line 235, in _feed
     obj = _ForkingPickler.dumps(obj)
   File "/usr/lib/python3.6/multiprocessing/reduction.py", line 52, in
 dumps
     cls(buf, protocol).dump(obj)
 TypeError: can't pickle _thread.lock objects

 ...

 }}}

 The same error appears in the MultiModule example "Asynchronous module
 run, setting finish = False and using temporary region".

 Using python 2.7.15rc1 all works fine.

-- 
Ticket URL: <https://trac.osgeo.org/grass/ticket/3799>
GRASS GIS <https://grass.osgeo.org>