Memory leak when reading TH2Poly from a tree

[Mary-Tim]

Dear expert,

I want to save the TH2Poly into a tree and read them in the other place.
The saving procedure works fun. But when I try to read the histograms, memory
occupy grows very fast.

Here are three simple scripts to show the problem:

testTH2Poly.C – Create a TH2Poly, fill it and then delete, no memory leak.

#include "TH2Poly.h"
#include "TRandom.h"
#include <iostream>

void testTH2Poly()
{
    for(int i = 0; i < 1000; ++i)
    {
        TH2Poly* th2 = new TH2Poly();
        th2->Honeycomb(0, 0, 1, 50, 50);
        for(int j = 0; j < 1000; ++j)
        {
            th2->Fill(gRandom->Gaus(0, 20), gRandom->Gaus(0, 20));
        }
        delete th2;
        std::cout << i << std::endl;
    }
}

genTH2Poly.C – Create a TH2Poly, fill it and then save into a tree, no memory leak.

#include "TH2Poly.h"
#include "TFile.h"
#include "TTree.h"
#include "TRandom.h"
#include <iostream>
void genTH2Poly()
{
    TFile* fout = new TFile("TestTH2Poly.root","recreate");
    TTree* tree = new TTree("test","");
    TH2Poly* th2 = new TH2Poly();

    tree->Branch("TH2", &th2);

    for(int i = 0; i < 1000; ++i)
    {
        delete th2;
        th2 = new TH2Poly();
        th2->Honeycomb(0, 0, 1, 50, 50);
        for(int j = 0; j < 1000; ++j)
        {
            th2->Fill(gRandom->Gaus(20, 10), gRandom->Gaus(20, 10));
        }
        tree->Fill();
        std::cout << i << std::endl;
    }
    fout->cd();
    tree->AutoSave();
    fout->Close();
}

readTH2Poly.C – Loop all the TH2Poly from a tree created by genTH2Poly.C, and do nothing. Even I have enable SetAutoDelete(), the memory occupy still grows very fast. Loop a 130M file causes 1.4G memory usage.

#include "TH2Poly.h"
#include "TFile.h"
#include "TTree.h"
#include "TBranch.h"
void readTH2Poly()
{
    TFile* fin = new TFile("TestTH2Poly.root");
    TTree* tree = (TTree*)fin->Get("test");

    TH2Poly* th2 = nullptr;
    TBranch* br_poly = nullptr;
    tree->SetBranchAddress("TH2", &th2, &br_poly);
    br_poly->SetAutoDelete(true);

    Long64_t numOfEntries = tree->GetEntries();

    for(Long64_t entry = 0; entry < numOfEntries; ++entry)
    {
        tree->GetEntry(entry);
        std::cout << entry << std::endl;
        br_poly->DropBaskets("all");
    }
}

Do you have any idea about that?

Best regards,
Ruiting

ROOT Version: v6.22/08
Platform: Linux
Compiler: cling/g++

---

[eguiraud]

Hello @Mary-Tim ,

valgrind --tool=massif should point exactly to the source of the memory allocations. Can you run readTH2Poly.C like valgrind --suppressions=$ROOTSYS/etc/valgrind-root.supp --tool=massif root.exe -l -b -q readTH2Poly.C+g and post the output file here?

Cheers,
Enrico

[Mary-Tim]

Hi @eguiraud ,

Thank you!
I tried to upload the log file but I got the message “Sorry, new users can’t put links in posts.”
So I past the plot from massif-visualizer at here:
Read a tree (28MB) which contents 200 TH2Polys causes 331MB memory usage.

Best regards,
Ruiting

[Mary-Tim]

Hi @eguiraud ,

@pcanal The problem is solved by enlarge the bufsize when create the branch of TH2Poly.
Thank you for your help!

Best regards,
Ruiting