Does creating a TCanvas load all libraries or something (very slow first load)

This seems to be an issue with any relatively recent (6.20 onwards) version of ROOT.

I’ve noticed that when simply doing:

root -e "TCanvas c;"

for the first time can take a very very (order of 30 minutes) time to run. Now, in this case ROOT is being provided through cvmfs and is part of my experiments software release stack (ATLAS). It does feel like simply constructing a TCanvas can trigger some really heavy load of data over cvmfs perhaps, although interestingly there isn’t this problem if I create, say, a histogram, and then draw it. That appears relatively quickly.

Sorry that this might not be easily reproducible, but I am hoping someone here might know why constructing a TCanvas perhaps causes lots of loading (of libraries or something?), which takes a long time for cvmfs for the first time.


root -e "TCanvas c;"`

Is not very fast also on Mac. May be @axel has an idea about it.

May be @vvassilev can help.

There has been at least one similar report (“unsolved”, see the last posts):

And possibly also this (though I’m not sure):

@will_cern If you use the “CernVM-FS” a lot, make sure your “CVMFS_QUOTA_LIMIT” is really big.

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