Problem using TCutG

ROOT
1

Hi,
I’ve got some trouble with the following piece of code (a version that creates the needed tree is attached to this post)

void tcutgdemo()
{
  gStyle->SetPalette(1);
    
  if (gDirectory == gROOT )
    TFile* f = new TFile("cuttest.root","recreate");

  TTree* tree = (TTree*) gDirectory->Get("bigtree");
  // create example tree, if no tree found...
  if (tree == NULL)
    {
      ...
    }
  
  double ulx[4] = {40.,-2.,40.,40.};
  double uly[4] = {10., 70.,70., 0.};

  double lrx[4]={-60,-20,-60,-60};
  double lry[4]={ 20,-50,-50, 20};
  
  TCutG* upperleft = new TCutG( "upperleft" , 4, uly, ulx );
  TCutG* lowerright= new TCutG( "lowerright", 4, lry, lrx );

  upperleft->SetVarX("mipposemc[0]");
  upperleft->SetVarY("mipposemc[1]");
  lowerright->SetVarX("mipposemc[0]");
  lowerright->SetVarY("mipposemc[1]");


  c1 = new TCanvas( "c1","c1");

  TH2F* ulhist = new TH2F("ulhist","ulhist",20,-100,100,20,-100,100);
  TH2F* lrhist = new TH2F("lrhist","lrhist",20,-100,100,20,-100,100);

  //  tree->Draw("mipposemc[0]:mipposemc[1]>>ulhist","mipposemc[0]>10&&upperleft","colz");
  tree->Draw("mipposemc[0]:mipposemc[1]>>ulhist","mipposemc[0]>10&&upperleft","box");
  tree->Draw("mipposemc[0]:mipposemc[1]>>lrhist","mipposemc[0]<-10&&lowerright","box");

  ulhist->Draw("colz");
  lrhist->Draw("colz same");

  //  delete upperleft;
  //  delete lowerright;
}

If you execute this script several times (usually two or three times) without touching anything. The root crashes.

root [0] .x tcutgdemo.C
TTree bigtree not found
root [1] .x tcutgdemo.C
Warning in <TH1::Build>: Replacing existing histogram: ulhist (Potential memory leak).
Warning in <TH1::Build>: Replacing existing histogram: lrhist (Potential memory leak).
root [2] .x tcutgdemo.C
Warning in <TH1::Build>: Replacing existing histogram: ulhist (Potential memory leak).
Warning in <TH1::Build>: Replacing existing histogram: lrhist (Potential memory leak).
root [3] .x tcutgdemo.C
Warning in <TH1::Build>: Replacing existing histogram: ulhist (Potential memory leak).
Warning in <TH1::Build>: Replacing existing histogram: lrhist (Potential memory leak).
root [4] .x tcutgdemo.C

 *** Break *** segmentation violation
(no debugging symbols found)
Using host libthread_db library "/lib/tls/libthread_db.so.1".
Attaching to program: /proc/20028/exe, process 20028
[Thread debugging using libthread_db enabled]
[New Thread -1218579808 (LWP 20028)]
0x011804de in __waitpid_nocancel () from /lib/tls/libc.so.6
Thread 1 (Thread -1218579808 (LWP 20028)):
#0  0x011804de in __waitpid_nocancel () from /lib/tls/libc.so.6
#1  0x011151c4 in do_system () from /lib/tls/libc.so.6
#2  0x00c8bd7f in system () from /lib/tls/libpthread.so.0
#3  0x005ef911 in TUnixSystem::Exec () from /opt/products/root/5.14.00/lib/libCore.so.5.14
#4  0x005efd2b in TUnixSystem::StackTrace () from /opt/products/root/5.14.00/lib/libCore.so.5.14
#5  0x005ede37 in TUnixSystem::DispatchSignals () from /opt/products/root/5.14.00/lib/libCore.so.5.14
...

I’ve tested this with ROOT 5.14 and ROOT 5.16. Surprisingly the number of calls needed to crash ROOT differs from try to try.

Are there some object ownerships rules, that I disobey or is there a different reason why this code does not work?

Cheers, J.
tcutgdemo.C (1.56 KB)

2

I suggest to modify your script as shown in the attachment.

Rene
tcutgdemo.C (1.6 KB)

3

Unfortunately deleting the TFile and reopen it doesn’t help if you place more code dealing with TCutG after my (minimal) example. I’ve attached a modified version of the “improved” example, where I essentially copy and pasted the code to create two more histograms.

Now ROOT crashes less often, but still crashes:

[code]root [0]
.x tcutgdemo2.C
root [1] .x tcutgdemo2.C
root [2]
*** Break *** segmentation violation
(no debugging symbols found)
Using host libthread_db library “/lib/tls/libthread_db.so.1”.
Attaching to program: /proc/21219/exe, process 21219
(no debugging symbols found)…done.
(no debugging symbols found)…done.
[Thread debugging using libthread_db enabled]
[New Thread -1218576256 (LWP 21219)]
(no debugging symbols found)…done.
(no debugging symbols found)…done.
(no debugging symbols found)…done.
(no debugging symbols found)…done.
(no debugging symbols found)…done.

0x0132d4de in __waitpid_nocancel () from /lib/tls/libc.so.6
Thread 1 (Thread -1218576256 (LWP 21219)):
#0 0x0132d4de in __waitpid_nocancel () from /lib/tls/libc.so.6
#1 0x012c21c4 in do_system () from /lib/tls/libc.so.6
#2 0x00599d7f in system () from /lib/tls/libpthread.so.0
#3 0x00836911 in TUnixSystem::Exec () from /opt/products/root/5.14.00/lib/libCore.so.5.14
#4 0x00836d2b in TUnixSystem::StackTrace () from /opt/products/root/5.14.00/lib/libCore.so.5.14
#5 0x00834e37 in TUnixSystem::DispatchSignals () from /opt/products/root/5.14.00/lib/libCore.so.5.14
…

[/code]

Sometimes even not before I leave ROOT:

root [0] .x tcutgdemo2.C
root [1] .x tcutgdemo2.C
root [2] .x tcutgdemo2.C
root [3] .q

 *** Break *** segmentation violation
(no debugging symbols found)
Using host libthread_db library "/lib/tls/libthread_db.so.

tcutgdemo2.C (2.23 KB)