PostProcessing (TrendingTask) output not shown by qcg

Dear Experts,
I used quality_control::postprocessing::TrendingTask with reductors from Common. I gathered its outputs in the qcg layout called Test_sbysiak in “PP” tab.
However they don’t show up there (they’re in “Loading” state).

I checked several ways to access these objects and here are the results:

  • in qcg->layout none is correctly shown
  • after clicking in the right top corner to open them in fullscreen TGraphs are correctly rendered but TH1 are not (e.g. TGraph and TH1)
  • the same happens if I access them from qcg->object list (TGraphs works, TH1 don’t)
  • via ccdb->ROOT browser both TGraphs and TH1 work (which proofs that they are proper ROOT objects, e.g. TGraph and TH1)

It seems to be quite simple gui error, however it would be good to have it working.
I am using QC v1.12.0.

Thank you and best regards,

Hi Sebastian,
I went to your link and it actually works on my setup :wink: Every plot there is displayed correctly (it takes 2-3 seconds to load them). I am using Firefox 87.0 on Ubuntu 18. Which browser and OS do you use?

@graduta @awegrzyn Could you please follow this up?


Edit: Sorr,y I didn’t go to PP tab. Those plots aren’t displayed. I will investigate if there is a problem on QC side.
Edit2: I can confirm what you are seeing and as for the QC framework, it seems that it behaves as I would have expected. It seems that the latest move to JSROOT in QCG might be an issue.

Thank you for raising the issue!

I confirm there is an issue with the TH1 object not being displayed.
For some reason JSROOT enters an infinite loop. I will follow up with the team and update once we have a fix.

Hi Sebastian,

Side question: why do you publish a TCanvas and not directly a TH1 ?


TrendingTask uses TTree::Draw to generate plots. This method produces TCanvases with TH1 (and/or TGraphs).

Thank you,

I have created a ticket:

We will follow it up in JIRA.

Dear all,

could this also be related to this issue we have on the TPC calibration QC?

We also want to display (rather large) TCanvases, which does not work on the QCG test webpage, and could also be related to JSRoot. Although, in a local QCG setup it is working, which is not understood up to now…


Hi @sbysiak ,

Following a short chat with JSROOT team, they identified the issue and it is now fixed.
I released the updated version of QCG on and your object is now available for plotting ( TH1 )

Thank you for raising the issue and please do not hesitate to contact us if anything else is needed!

Kind regards,

1 Like

Hi @sheckel ,

The issue you have linked is unrelated to the one posted by Sebastian. I will continue with more details on the ticket itself so that we do not create any confusion.

Thank you,