multithreading with python

Replies to This Discussion

Permalink Reply by Andrew Heumann on July 14, 2015 at 8:23am

in my experience, ghpythonlib.components and ghpythonlib.parallel are NOT FRIENDS. You can pretty readily parallelize rhinocommon functions - but trying to parallelize the "virtual component" logic from a grasshopper component seems to cause some kind of memory leak, with progressively worse performance. 

See also these posts: 

http://discourse.mcneel.com/t/ghpython-parallel-component-slower-th...

http://discourse.mcneel.com/t/new-ghpython-issues-crashing-multithr... 

Permalink Reply by Jonah Hawk on July 14, 2015 at 11:04am

Thanks for the reply and tips Andrew. I've wondered why there are not heaps of posts using .parallel. I've suspected that we may have to write our own ray intersect function to get this to work reasonably fast.

Permalink Reply by dustin on July 24, 2015 at 4:49pm

Yes, thank you for the links, Andrew, definitely helpful in explaining the behavior we were getting.

Permalink Reply by Giulio Piacentino on July 14, 2016 at 10:23am

Good news! The library is now rewritten in Rhino WIP. http://discourse.mcneel.com/t/new-version-of-ghpythonlib-components...

Permalink Reply by Nik Willmore on July 14, 2016 at 5:25pm

Great news. But learning Rhinocommon opens up a lot more command options like tolerance and what about the old problem that node-in-code can only access the default mode of a component that has options for several in its little tag along the component bottom?

One aspect to parallel I had to appreciate was having to add an index entry paired to my input data that survived the parallel function reordering of an input list, so I could re-sort the output to correspond to the input list.

Permalink Reply by Giulio Piacentino on July 15, 2016 at 10:42am

Hi Nik

thanks for the feedback. RhinoCommon can be overwhelming, while ghcomponentlib is used a lot because it is structured exactly like Grasshopper. It is also the only way to access, say, Voronoi or any third-party add-on. The default is still what you are able to access. Is there a function in particular that is giving you grief?

Just something to watch for: we cannot use normal lists in parallel. It is not safe. Things might just not work. Also, sorting is non-threaded, so adding a sort afterwards (if elements are many) will be very expensive and on one thread, again.

Just some ideas,

Giulio
--
Giulio Piacentino
for Robert McNeel & Associates
giulio@mcneel.com