Loading libFWCoreFWLite and using chain.GetEntries()

Hello!
I have a problem with my macros with FWLite.
I need to load the libFWCoreFWLite to define the object “vector bj”, but when I do this, I get this error :
Error: Symbol chain is not defined in current scope test_plot.C:19:
Error: Failed to evaluate chain.GetEntries()
*** Interpreter error recovered ***

If I remove the part of macros wich loads the libFWCoreFWLite,
then “chain.GetEntries()” works, but a problem with identification of “vector bj” appears of course.

So, please, may be somebody can help me, why it happens?
That is the contents of my macros:


void test_plot() {

if (gSystem->Load("libFWCoreFWLite") == 0) { // if not loaded yet, load it
 AutoLibraryLoader::enable();

}

 TChain chain("Events");
 chain.Add("SingleTopMuEvents_1.root");
 chain.Add("SingleTopMuEvents_2.root");

 TH1F* h = new TH1F("h","",50,0,250);

 TBranch * topBjets = chain.GetBranch( "TopJets_selectedTopBJets__StEventReco.obj" );

// Loop over events and fill histogram
Int_t nev = chain.GetEntries();
cout << "nev = " << nev << endl;

vector bj;
for( int ev = 0; ev < nev; ++ev ) {
topBjets -> SetAddress( & bj );
topBjets -> GetEntry( ev );

 double pt=bj[0].pt();
 h->Fill(pt);

}

gStyle->SetOptStat(0000);
gStyle->SetCanvasBorderMode(-1);
gStyle->SetCanvasBorderSize(1);
gStyle->SetCanvasColor(10);

h->SetLineColor(2);
h->SetLineWidth(3);

TCanvas* myCanvas = new TCanvas(“myCanvas”,“Jets”,100,10,800,800);
myCanvas->SetFillColor(10);
myCanvas->cd();

h->Draw();

TLegend *legend = new TLegend(0.75,0.75,0.95,0.95,"",“NDC”);
legend->AddEntry(h,“bj[0].pt”,“l”);
legend->Draw(“Same”);
myCanvas->Update();

// output:
TString gif(“bj[0]_new.pt.gif”);
myCanvas->Print(gif);

}


P.S. Files SingleTopMuEvents_*.root has several trees, one of them calls “Events”

Thank you in advance.

Hi,

A similar problem has been reported but not yet understood. The closest we got was that one (or more) library that is being loaded is somehow reset the interpreter environment. Please report this to your CMS fw guru, this might help them in providing us with a manageable example to reproduce the problem.

Cheers,
Philippe