DVR Parallel Read Access

[mcduff]

In LabVIEW 2017 there is a new DVR option, Parallel Read Access. In this mode...

When the border node on the right is unwired, LabVIEW allows multiple, concurrent read-only operations and does not modify the data value reference.

I was wondering whether anybody has tested this mode for speed. In some VIs, sorry I cannot post them, it appears slower while in others faster. I am not sure when to use this mode. For me, it seems any read only operation should be better in this mode (even just a single access), however, in my testing this is not the case.

Anybody else out there test this new feature and can offer some thoughts?

Thanks

mcduff

[DonhJoe]

Hi,

Could you post an example code of this?

Regards!

[mcduff]

I can't post my application due to company policy, but something similar to the diagram below.

[Jacobson-ni]

I ran the code below and saw pretty comparable results between the read only and the read/write.

Let me know if you see much difference in speed with the above 

[mcduff]

Maybe my example was bad. For this other case I can describe and show some code. I am downloading millions of points from a DAQ device, before plotting the data I do a Min/Max type of decimation so I plot a few thousand points instead of a few million. Below is the outer VI

The array is not being modified at all in this case, just read.

The subVI inside the in-place structure looks like this

Maybe its slower because I'm reading chunks of the array, not really sure. I do know if I put High Precision timers on the outside of the loop it is faster without the Read Only mode.

Thanks for looking into this.

mcduff

[kleenexsmoke]

Am I missing something here?  Does this not work for Classes in DVRs?

[Jacobson-ni]

The read-only feature does not work with classes in 2017 although this is a bug. CAR 671221 was filed to address this.