#include "TFile.h"
#include "TSystem.h"
#include "TTree.h"

void treesize (Int_t save_num = 10, Int_t out_num = 100, Int_t run_num = 1000) {
  Float_t f1,f2,f3;
  Int_t i1,i2,i3;
  TFile *fFile = new TFile("file.root", "RECREATE");
  TTree *fTree = new TTree("fTree","Tree Name",0);

  fTree->Branch("f1",&f1,"f1/F");
  fTree->Branch("f2",&f2,"f2/F");
  fTree->Branch("f3",&f3,"f3/F");

  fTree->Branch("i1",&i1,"i1/F");
  fTree->Branch("i2",&i2,"i2/F");
  fTree->Branch("i3",&i3,"i3/F");

  TDirectory* savedir = gDirectory;
  for(Int_t i=0;i<run_num;i++) {
    i1=1;i2=2;i3=3;
    f1=1.;f2=2.;f3=3.;
    if(i%out_num==0)printf("Output %.1fkB",fFile->GetBytesWritten()/1024);
    fTree->Fill();
    if(i%save_num==0)savedir = gDirectory;
    if(i%save_num==0)fFile->cd();
    if(i%out_num==0)printf(" to %.1fkB",fFile->GetBytesWritten()/1024);
    if(i%save_num==0)fTree->AutoSave();
    if(i%out_num==0)printf(" to %.1fkB",fFile->GetBytesWritten()/1024);
    if(i%save_num==0)fFile->SaveSelf();
    if(i%out_num==0)printf(" to %.1fkB",fFile->GetBytesWritten()/1024);
    if(i%out_num==0)printf("\n");
    if(i%out_num==0)gSystem->Exec("du -k file.root");
    if(i%save_num==0)savedir->cd();
  }
  fFile->Write();
  fFile->Close();
}