Branch Size of tree w/ large number of entries

[Tanvi_Wamorkar]

Dear experts,

While running a code on a root file, which has 13095658 entries, I run into these error messages:

Please correct me if I am wrong, but I think this might be because the branch size is not big enough to handle so many entries.
For eg: I fill a branch of the tree :(snippet of my code )

def MakeSkimmedTree(self):
outTree = TTree(“H4GSel”, “H4G Selected Events”)
SetOwnership(outTree,0)

  outTree.Branch('p1_pt', self.p1_pt, 'p1_pt/D')
  outTree.Branch('p2_pt', self.p2_pt, 'p2_pt/D')
  outTree.Branch('p3_pt', self.p3_pt, 'p3_pt/D')

How can I tackle this error?

Many thanks in advance,
Tanvi

[pcanal]

The problem seems to be in (one of) the input TTree (i.e. unzip-ing, ReadBasketBuffer) and this looks like the file is corrupted on disk …

Cheers,
Philippe.

[Tanvi_Wamorkar]

Thanks for the quick reply Philippe!
One thing I should mention is that this file was created by hadd’ing multiple files. When I try to run my analyzer code on some of the individual files, everything works fine. I only get these error messages when I run my code on this combined file (created by hadd’ing).

Could it still be due to the same reason you mentioned?

Thanks,
Tanvi

[pcanal]

How were the original file produced (was it with an old version of Geant4)?

[Tanvi_Wamorkar]

I am not sure about that since I didn’t produce them. Would the production method have something to do with this? My analyzer code runs fine on other files (belonging to different Runs).

Is there a way to allocate more memory to a particular branch? I want to check if I am running out of memory while filling the trees

[pcanal]

It is not a matter of allocating ‘more’ memory to a particular branch.

In some older version of Geant4 there was a bug that prevented the merging of several files smaller than 2Gb into a file larger than 2Gb.

To work around the problem force hadd into ‘slow’ merging option

hadd -O ....

Cheers,
Philippe.

[Tanvi_Wamorkar]

Thanks for the suggestions Philippe!