> > Hi all,
> > I get this warning when I run anaDisplay.exe (analyzer display mode) of the old
> > Rootana analyzer. It seems to be because the analyzer cannot keep up with the data
> > gathered by my frontend. The same issue seems to happen when I run the newer
> > "manalyzer_example_root_graphic.exe" in graphical mode (-g). Is my computer cpu
> > just not powerful enough to run both the data acquisition and the graphical
> > analyzer simultaneously? Both the frontend and analyzer run on the same PC.
> > As always, thanks for the help!
> > Isaac the intern
> Hi Isaac,
> It is certainly possible that your analyzer cannot keep up with the data taking. It will depend (at least partly) on what you are trying to do in your analyzer. Suppose you are taking 1000Hz of events from some waveform digitizer. If you are trying to do something simple (like count how many bytes are in each data packet) then your analyzer will probably be able to keep up with the data taking. But if you are trying to do some very complicated maximum likelihood fit to each waveform, then it is possible that your computer (or any computer) would not be able to keep up with the data taking. In that case maybe your analyzer is only able to process 100Hz of data or 10% of the events (for example).
> But it is not always a problem if your analyzer can't keep up. The goal of the online analyzer is to allow you to check data in real time. If you wanted to calculate the pulse height distribution of hits in your waveforms, then it is probably fine that you are only able to process 10% of the events online. It might take you a little longer to accumulate your statistics for your online plots, but your online analyzer data is still useful.
> On the other hand, there is other types of online analysis where it is important to process every event. For instance, suppose you are trying to calculate online the rate of a certain type of event that involves making cuts in your online analysig. In that case you will want to be analyzing every event; missing 10% or 90% of events will bias your online analysis.
> So that message is a warning; if you are doing an online analysis where it is critical that you process every event, then you have a problem if you see that message. In that case you need to figure out how to speed up your online analysis. You will need to use a profiler or some other tool to optimize your code.
> It should be noted that the display itself can often be a limiting part of the online analyzer. You might be able to process 1000Hz of waveform data, but you certainly can't update your plots at 1000Hz; so you need to take care with the updating and display of your plots if you really care about speed.
Thank you for the thorough answer. I can now see how this feature is important. Also, I was getting turtle speeds for my analysis rate.
I found out that it was because I was 'drawing/updating' my histograms for every event. I'm new to ROOT and I didn't realize how badly these
functions slow down your system.