[Gate-users] filemerger...

Park MinJae MJ at ToTi.us
Tue Oct 23 13:10:23 CEST 2007

Dear Jan,

1. Environment setting...
I set as following...

but there is a strange thing...
Even though there is no entry in latest_event_id, small root files can be
merged with gjm...
[when TBrowser load the merged file, root is trying to recover 8 keys, Hits,
Singles, Gate, latest_event_ID, etc...]

2. ROOT version...
I am using 5.12 version...
Based on your mail, 5.12 version is problem, right?

3. Loading individual root files...
I can load them in TBrowser without any problem...

4. Cluster benchmark...
I just have started the benchmark with clustering as you said...

I got some problem with installing root 5.14 and 5.16...
I guess it's library problem with xpm...
I start to install 5.14 again...

and I start to use TChain...but the way to connect Singles is a little
I use the following code...
TFile *f = new TFile("duals10.root");
TTree *Singles = (TTree*)gDirectory->Get("Singles");

but when I use the following code...
TChain chain("T");
TTree *Singles = (TTree*)gDirectory->Get("Singles");

ROOT said...illegal pointer to class object Singles...at

I guess there is another way of using TChain than TFile...


//  Park MinJae
//  SNU BME Ph.D. Candidate
//  DialTo:+82-17-711-7809
//  MailTo:MJ at ToTi.us
//  Make the Dream True...

-----Original Message-----
From: gate-users-bounces at lists.healthgrid.org
[mailto:gate-users-bounces at lists.healthgrid.org] On Behalf Of Jan De
Sent: Tuesday, October 23, 2007 7:48 PM
To: Samuel BURG
Cc: Users Gate; Park MinJae
Subject: Re: RE : RE: [Gate-users] filemerger...

On Tue, 2007-10-23 at 12:08 +0200, Samuel BURG wrote:
> Dear MJ,
> I have also lot of problems with gjm.
> One 'easy' solution is to do a 'fast merge' with gjm and the to use a
> TChain under ROOT to post-process your (multiple files) data.
> Pro : it works, no need to update any code
> Cons : files 25% bigger, not very fun

This isn't the case if you only merge the tree or leaves of the tree
that you need. If you disable the Gate ntuple, then spect root files are
quite small.
The file merger should work on all root files generated by Gate, fast
mode or not.

If you experience problems then check the following:
- are your environment setting set for cluster gate ? if they are, then
any root file generated should have a latest_event_id histogram with an
entry in it. ->Park MJ: your root files have no entry in that histogram.

- are you using a recent root version ? Try root v5 at least. ->Park MJ:
merging your files with an older root version gave a segmentation fault.
With root v5.12 it displays an error about an empty latest_event_id

- can you load the individual root files before merging ? You should be
able to open them with root and view the contents with a TBrowser.

- you can test all this with the cluster benchmark

If you are still having a problem then send a test case like Park MJ


MScE Jan De Beenhouwer
Ghent University Hospital
De Pintelaan 185
Block B - 5th floor
B-9000 Ghent
Tel. +32-9-240.43.26
Fax: +32-9-240.33.90
E-mail: <Jan.DeBeenhouwer at UGent.be>
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