[Paraview] Comparison of Visit and ParaView development

[Utkarsh Ayachit]

> but I always wondered about the development process of VTK/ParaView with respect to bug
> reports. There seem to be a huge number of reported bugs for ParaView (and a
> few for VTK), ranging from crashes to incorrect functionality to feature
> requests.

Bugs often get prioritized by several of the customers/community
members that drive the development of ParaView. While several others
get fixed as developers notice them. As you said, bug trackers does
accumulate several reports. Hence it's good to make some noise on the
mailing list to get some attention when you report a bug, for example.
While we do endeavour to monitor the bug tracker, in practice it's
hard to stay on top of it and things can easily slip down the cracks.
For example, I don't think I ever even saw the bugs you mention.
Several were indeed easily answerable.

> A second "handicap" in this respect is
> undoubtedly the fact that KitWare is a business and so has different
> priorities than a bunch of hackers working mostly in their spare time on
> their pet project.

Sure, Kitware is a business, but not most of us here are driven by the
open source ideals and everything that it brings -- community, greater
good etc. etc. Many of us do respond in our spare or personal time
just because we enjoy it -- when we could very easily be simply
catching up on the latest Game of Thrones gossip :). Of course, life
is always less than ideal and deadlines and requirements of ongoing
projects often dictate how things get prioritized, but that doesn't
mean we are any less driven. At the same time, these are community
projects. Community members using ParaView and developing with it are
encouraged to take over bugs, ask for assistance on how to track them,
as needed. Everyone will only be glad to help. We've even made it
easier with Gitlab to get community changes reviewed and tested and
merged. There have been a few new folks contributing since that
happened -- kudos to them -- but just looking at the kinds of
questions we answer on the mailing list, there are clearly a lot more
people with the know how out there who just don't contribute back.

> But basically anything reported these days immediately gets status "backlog"

"backlog" is just the default state.

> Furthermore, ParaView seems quite easy to segfault and it happens even with
> moderately complex pipelines and modest datasets. Parallel volume rendering
> has been broken for ages

There have been quite a few recent announcements that went into
revamping the volume rendering code.
https://blog.kitware.com/paraview-5-0-1-release-notes/
https://blog.kitware.com/volume-rendering-enhancements-in-vtk/
https://blog.kitware.com/paraview-5-0-0-rc1-available-for-download/

> So the comment above about code quality making ParaView stand out from other
> visualization tools is a bit a stretch in my opinion. I would certainly not
> call ParaView "stable". In fact, in the introductory scivis courses we teach
> with ParaView we always warn people that crashes are to be expected
> regularly and even during the course assignments they sometimes happen.

Please do report issues with information on how to reproduce them. The
whole team including members from outside Kitware, like Alan Scott
from Sandia and others work tirelessly to keep things stable. But
note, ParaView is also constantly pushing the envelope. There are
always a hoard of new features being added to support new usecases.
That does mean more opportunities to make mistakes. Thankfully,
several community members already help out a lot with testing and
making sure things continue to work, so the picture is really not that
bleak. There are community members ensuring things build and deploy on
esoteric HPC systems we don't have access to, there are folks
deploying on various linux distributions and working with us to
address any issues, the list goes on and on!

The moral of the story is: just speak up and grab someone's attention,
and if that fails, just grab your coding toolbox and dive in -- how
bad can it be :)!

Utkarsh