Darren's Occasional Nugget 08/14/2008

[Darren]

Here's one of the more overlooked new "features" in LabVIEW 8.6.  The size of VI files on disk is reduced, sometimes dramatically, due to some new compression techniques we're using in saving/loading VIs.  Here are some examples of VI-based features that I've worked on and their respective file sizes in LabVIEW 8.5 and 8.6:

VI Metrics codebase

LabVIEW 8.5 - 346 KB

LabVIEW 8.6 - 186 KB

LLB Manager codebase

LabVIEW 8.5 - 2,954 KB

LabVIEW 8.6 - 1,615 KB

VI Analyzer UI codebase

LabVIEW 8.5 - 10,149 KB

LabVIEW 8.6 -  5,589 KB

So as you can see, these collections of VIs have decreased in size about 45-50%...I've seen some cases where VIs are more than 75% smaller on disk in LabVIEW 8.6.  In these days of cheap 300 GB hard drives, disk space isn't really a concern, but I figure these smaller file sizes will have other benefits, like faster VI downloads, less space taken up by SCC backups, etc.

-D

P.S. - Check out past nuggets here.

[altenbach]

Darren, I have not tested that, but is there also a similar size benefit for built applications?

[Darren]

I just checked by building an EXE out of the main VI Analyzer UI VI:

LabVIEW 8.5 - 2,186 KB

LabVIEW 8.6 - 1,603 KB

So it appears we're gaining some benefits of the file compression in 8.6, but it's not as large as it was for VI files.  That makes sense to me, since the diagrams of most/all VIs are removed during the build process, which will inherently reduce the amount of compression that takes place.

-D

[Mythilt]

Hmm, does this impact .llbs?  I ask because I seem to remember being told that .llb's use compression as well.

[Darren]

LLBs do have their own compression that has been around forever, but I believe the compression inherent to LLBs pales in effectiveness to that implemented for VIs in LabVIEW 8.6.  Note that all of the examples I cited in my initial post primarily consist of VIs in LLBs.

-D

[Kjell-E]

Pardon me for performing thread necromancy, but I was wondering if this feature could be related to how (in 8.6) I've noticed how some wires and objects (reference nodes etc) can sometimes "shift" or nudge when I open a diagram. I don't have a handy example of screen shots to show right now, but basically I'll have all straight and nice wires on my diagram, then I'll save the vi, exit out of LV and then next time I open it some wires have inexplicably obtianed some minor kinks and sometimes even moved  a property node or similar a little bit.

I am not sure (memory again) but it could be that this only happens if I opened the VI on a computer with a different monitor resolution such as when developing code on my main computer, uploading it to a repository and then "updating" the files on say a PXI controller from the repo and opening on the PXI controller.

Nothing breaks or gets re-wired, its just frustrating to have a nicely laid out diagram and have it "randomly" "messed up" just from opening it on a different computer. Anyway, I saw this thread and I started thinking about the problem/feature again and figured maybe it could be related to how the files are compressed. Maybe the compression is not as loss-less as originally thought?

[Neil.Pate]

Its probably not due to the compression as its (I am assuming!) totally lossless compression rather than lossy (ie jpg type) compression.

I have seen this before when moving between PCs with different DPI on the screens.

[Darren]

I seriously doubt VIs are being changed by the different save format in LabVIEW 8.6.  The only times I've seen diagrams get messed up is with different DPI settings (as nrp mentioned), and with moving between XP and Vista, where the default Vista font is uglier bigger than the default XP font, which causes any diagram object with text in it to be slightly shifted, which causes connected wires to shift as well.  Obviously this can happen when moving between Windows/Mac/Linux as well.

[Kjell-E]

AHA!

In our case, I seem to remember the PXI controller running VISTA *yuck* same as my laptop *double-yuck* so I guess it is the DPI thing. I've just never experienced that before so naturally the easy thing was to blame the newer LV that I'm using at work compared to at school. Thanks for sharing all of your insights!
Thanks!