Extremely long startup time when loading dictionaries with pyroot about root

[dpiparo]

Hi @MarkusFrankATcernch ,

I am sorry you experienced this issue.
We know that importing ROOT using LCG releases, perhaps on lxplus nodes can be slow. For this reason, we implemented a first pack of optimisations in PyROOT for the ROOT release 6.30. Unfortunately, this is not available yet in any LCG stack.
Is it easy for you to perform the same measurement with a dev3 lcg stack? That would allow you to use ROOT master and benefit from the latest optimisations.
I know this might not be a solution to the problem you report, but it might be a start.

[MarkusFrankATcernch]

Hi @dpiparo,

the problem is not the top-short-term fix, but the longer term. I started to see this behavior in summer and reported it to Axel, when I could not use the LCG views anymore to build dd4hep. Unfortunately Axel was highly busy since and I am glad you now take care!

However, now I also start seeing the behavior also in the LHCb-online nightly builds, because tests sometimes tend to fail, because images activated from python using pyROOT simetimes take several 100 seconds (I have set the timeout now to 300 seconds) to start up. This is not really good anymore given that the dictionaries for these apps are far from gigantic and starting (during the same test run) the same app using some kind of ini files does not at all suffer from this problem.

Tell me if I should test using a private build with root master.

Markus