Re: CSS X-Y Graph

[Andrew Johnson <anj@aps.anl.gov>]

Hi Mark,

On 2012-02-24 Mark Rivers wrote:
> While Janet is looking at the plot widget, there is a serious performance
> problem that should be fixed if at all possible.  If you create a waveform
> with a large number of elements, so that the plot update is rather slow,
> then you can clearly see the following: when a new array is posted the
> plot widget first replots the existing array, and then plots the new
> array.  This slows things down by a factor of 2, which is very significant
> when the number of elements is large, and the plot is really slow anyway.

Are you using the technique Eric described, i.e. pointing the count to a 
separate PV which reads NORD?  I could see that causing the double-plot 
behavior if MEDM gets a count monitor event before the new array data arrives. 
Since MEDM is single-threaded it may not be possible to interrupt a plot once 
it starts, unless you want to be able to insert some kind of settling delay 
before it actually starts the plot.

That's another reason to make the widget able to use the new dynamic array 
sizing feature, since the array data and its size will arrive in the same 
monitor event.

- Andrew
-- 
Never interrupt your enemy when he is making a mistake.
-- Napoleon Bonaparte