Problem with TChain

Hi - I’m using 3.04/02 and having a strange problem.

I have a ten chain files, each with a few hundred files. Most of these individual files are pretty small.

For each chain, I run a filtering algorithm which then outputs a single ROOT file. It uses TFile::Write().

This filtering algorithm works fine on all but one of my chain files. When I run on this bad chain file, I get an output ROOT file of size 2k instead of 500k or so. But, I don’t get any error messages.

So, I went through my bad chain, and commented out certain individual files. I found that commenting out some files does remove this problem. However, if I create another, smaller chain with one of the “bad” files, I don’t have this problem - so the behavior is not consistent.

Also - instead of dividing into 10 chain files, I divided into 6 chain files. Once again, I had one problematic chain. However, the weird thing is that the bad 1/6 chain file had no overlapping files with the bad 1/10 chain file.

The problem also doesn’t appear to be dependent on the number of files in the chain, since the chain with the largest number of files has no problem.

So without error messages or any kind of consistent error behavior, I’m really having problems trying to debug this problem. Any ideas? Thanks for any help.

Hi,

I would recommend upgrading to 4.00/03 or 04 first and try again.

If you are using TTree::CloneTree has some severe limitations which were lifter in 3.05/06.

If after upgrading to 4.00/03, you still see this weird problem, please send me enough info to reproduce it.

Cheers,
Philippe.