I am trying to merge serveral ROOT files using the hadd tool.
Each file contains a single THnSparse histogram.
I have no problems while the ROOT files are small, but when I am trying to merge bigger THnSparse objects (~500 MB each), I get the following error:
Error in <TExMap::FindElement>: table full
Error in <TExMap::Expand>: slot 0 not empty (should never happen)
and the program crashes.
I can not reproduce the error with smaller files, so I am not attaching them here. If necessary, I can upload the files on a public web server.
My ROOT version is 5.34/01.
Interesting. Yes, would you be able to give me access to the files, please?
I am having the same issue while trying to merge several ROOT files containing THnSparse histogram. Was there a solution to this problem?
I don’t remember finding any solution to this problem.
I guess @Axel will need access to your files for inspection.
BTW. Is it possible that the merging process tries to create a histogram which is too big to be stored in a ROOT file (there exists a 1GB TFile buffer/basket limit)?
The file can be found at the link above. I am trying to add > 1000 of such type of files. I am not sure if this is a size issue, I have merged same number of similar type of files without THnSparse (however those were bigger in size).
thank you for sharing the files. Note that the original post was from 2012, so it might or might not apply.
It would be great if you could open a bug report at https://sft.its.cern.ch/jira/projects/ROOT with this same link to the files and also a minimal reproducer (the smallest snippet of code that we can run and that reproduces the problem). That would greatly help us figure out what the problem is.