Problems with hadd

Hi all,

I have a question regarding hadd in 5.26.00 and merging files with trees and histograms. Can it happen that the trees are merged, but not the histograms?

I saw the following problem:
I run my script and create several root files (output.X.root) in which the number of total entries in the tree is counted in a special histogram. Then I merge those files (output.root) and then I slim the tree (output.slim.root). For some calculation (luminosity of the sample) I need to remember the total number of original entries and for saving some space I remove some entries from the tree I found in some cases that right after the merging the number of entries in the tree were smaller as the entries in the histogram.

Unfortunately, I cannot reproduce it right away, because I ran on the grid over a large number of files. The original files and the merged file are deleted and I only have the final output.slim.root file. So far, I have only checked one job and I was lucky that I wrote out the number of entries in the log files. I have not seen any error message from hadd in the logs.

Anyway, I was wondering if that could theoretically happen or if I should try to track down the problem somewhere else.

Thanks
Duc Received on Tue Nov 22 2011 - 15:44:19 CET