I’ve done a test adding two files a.root and b.root, each 2.2G. I compare the times to add them using hadd in root versions 5.24, 5.22, and 5.20 below, all 64-bit.
time hadd aplusb.root a.root b.root
Version 5.24 (64 bit)
Version 5.22 (64 bit)
Version 5.20 (64 bit)
Original post below:
Is anyone familiar with hadd? I’ve been using it to merge files (TTree files, not just histograms) and it has worked very well. I recently moved to root version v5.24(64bit) and notice hadd takes much longer to complete than it used to in v5.18(32bit).
As a demonstration, I have 3 ntuples, fileA.root,fileB.root, and fileC.root. Each file is 1.2G.
When I do:
time hadd outfile.root fileA.root fileB.root fileC.root
these are the times I get:
ROOT v5.24 (64 bit)
ROOT v5.18 (32 bit)
22 minutes vs 48 seconds . . . ??? Any help is much appreciated.