TRatioPlot seg fault in PyROOT

ROOT
1

If I try to run the ratioplot1.C tutorial ($ROOTSYS/tutorials/hist/ratioplot1.C) equivalent code in PyROOT (see below) creating a TRatioPlot causes a seg fault. Does this occur for other people on similar architectures, and is there currently a way to create ratio plots in PyROOT other than the way shown in the ratioplot.py tutorial ($ROOTSYS/tutorials/pyroot/ratioplot.py)?

The plot will be created, but the segfault happens when ROOT.TRatioPlot(h1, h2) is called.

System Information:

$ uname -a
Linux mcf-ThinkPad-Edge-E540 4.4.0-51-generic #72-Ubuntu SMP Thu Nov 24 18:29:54 UTC 2016 x86_64 x86_64 x86_64 GNU/Linux
$ root-config --version
6.09/01
python --version
Python 3.5.2 :: Anaconda custom (64-bit)

ratioplot1.C equivalent code:

import ROOT

if __name__ == '__main__':
    c1 = ROOT.TCanvas("c1", "A ratio example")
    h1 = ROOT.TH1D("h1", "h1", 50, 0, 10)
    h2 = ROOT.TH1D("h2", "h2", 50, 0, 10)
    f1 = ROOT.TF1("f1", "exp(- x/[0] )")
    f1.SetParameter(0, 3)
    h1.FillRandom("f1", 1900)
    h2.FillRandom("f1", 2000)
    h1.Sumw2()
    h2.Scale(1.9 / 2.)
    h1.GetXaxis().SetTitle("x")
    h1.GetYaxis().SetTitle("y")
    rp = ROOT.TRatioPlot(h1, h2)
    c1.SetTicks(0, 1)
    rp.Draw()
    c1.Update()
    c1.SaveAs("ratio.pdf")
    c1.Destructor()

seg_fault.out.txt (5.43 KB)

2

I see the crash to with:

from ROOT import *

c1 = TCanvas("c1", "A ratio example")
h1 = TH1D("h1", "h1", 50, 0, 10)
h2 = TH1D("h2", "h2", 50, 0, 10)
f1 = TF1("f1", "exp(- x/[0] )")
f1.SetParameter(0, 3)
h1.FillRandom("f1", 1900)
h2.FillRandom("f1", 2000)
h1.Sumw2()
h2.Scale(1.9 / 2.)
h1.GetXaxis().SetTitle("x")
h1.GetYaxis().SetTitle("y")
rp = TRatioPlot(h1, h2)
c1.SetTicks(0, 1)
rp.Draw()
c1.Update()
c1.SaveAs("ratio.pdf")
$ python ratioplot1.py 
Info in <TCanvas::Print>: pdf file ratio.pdf has been created

 *** Break *** segmentation violation
[<unknown binary>]
[<unknown binary>]
[/Users/couet/git/roottrunk-bin/lib/libGpad.so] TRatioPlot::~TRatioPlot() /Users/couet/git/roottrunk/graf2d/gpad/src/TRatioPlot.cxx:162
[/Users/couet/git/roottrunk-bin/lib/libPyROOT.so] PyROOT::op_dealloc_nofree(PyROOT::ObjectProxy*) /Users/couet/git/roottrunk/bindings/pyroot/src/ObjectProxy.cxx:65
[/Users/couet/git/roottrunk-bin/lib/libPyROOT.so] PyROOT::(anonymous namespace)::op_dealloc(PyROOT::ObjectProxy*) /Users/couet/git/roottrunk/bindings/pyroot/src/ObjectProxy.cxx:213

it crashes in the TRatioPlot destructor. No idea why yet. The pdf file is created properly though…

I am running on Mac with ROOT master.

3

Fixed in the master. Thanks to have seen it.

4

Great! So the fix has been committed and I should just be able to pull down the latest commit (at root.cern.ch/git/root.git) and rebuild, correct?

5

Yes

6

Hi, @couet. This was fixed in ROOT v6.09 (thanks!), however it still exists in ROOT v6.08.

I am noticing the same behavior we say back in December on lxplus with this configuration:

$ uname -a
Linux lxplus022.cern.ch 2.6.32-642.15.1.el6.x86_64 #1 SMP Fri Feb 24 16:56:37 CET 2017 x86_64 x86_64 x86_64 GNU/Linux
$ root-config --version
6.08/07
$ python --version
Python 2.7.13

Can the fix that you put into ROOT v6.09 also be applied to the patches for ROOT v6.08? I would like to use TRatioPlot in the ROOT v6.08 available on lxplus through CVMFS as described in this issue here.

7

Yes it was fixed in master only (6.09). We usually back port the blocking problems or those which can’t be turned around. If it is the case I will port it back.

8

Hi @couet, so for this problem are you able to back port it?

9

The working version from the master has been imported in 6.08

10

Okay, so I assume that means it is now in the master branch for 6.08. Sorry to ask a stupid question, but is there a way for me to use this on CVMFS besides trying to find it in the nightlies? That is, is there someway for me to source it in a similar fashion to an LCG release,

$ . /cvmfs/sft.cern.ch/lcg/releases/LCG_88/ROOT/6.08.06/x86_64-slc6-gcc62-opt/ROOT-env.sh

?

11

Until we release a new patch release of v6.08 it’s only in the nightly builds. We will likely release the next patch release during the second half of April.

Axel

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