Re: ReadObj memory leak?

From: Rob Snihur <snihur_at_fnal.gov>
Date: Fri, 18 Mar 2005 01:07:55 -0600

Hello Philippe,
Thank you for your prompt reply.
I tried adding to my file m2.C the following line:   if ( obj != NULL ) delete obj;
I got the same error as before
(both in ROOT 4.00/08, and in ROOT 3.05/07).

Next, I tried your alternative suggestion:   TFolder* obj = (TFolder*)key->ReadObj(TFolder::Class()); This produced the error below (in ROOT 4.00/08).

Finally, I tried your last suggestion:
  TFolder *obj; f->GetObject(k,obj);
This reproduced my original error.

Are you able to reproduce my results?
Any other suggestions?

thanks again,
-rob

root [0] .x m1.C(1,10)
i=1
Error: Can't call TKey::ReadObj(TFolder::Class()) in current scopePossible candidates are...

filename       line:size busy function type and name  (in TKey)
(compiled)        0:0    0 public: virtual TObject* ReadObj(void);
filename       line:size busy function type and name  (in TNamed)
filename       line:size busy function type and name  (in TObject)

Error: non class,struct,union object $key used with . or ->Error: Can't call TKey::ReadObj(TFolder::Class()) in current scope FILE:m2.C LINE:18 Possible candidates are...

filename       line:size busy function type and name  (in TKey)
(compiled)        0:0    0 public: virtual TObject* ReadObj(void);
filename       line:size busy function type and name  (in TNamed)
filename       line:size busy function type and name  (in TObject)

Error: Symbol key is not defined in current scope FILE:m2.C LINE:18 Error: Failed to evaluate key->ReadObj(TFolder::Class())*** Interpreter error recovered ***

Philippe Canal wrote:

> Hi Rob,
>
> Only Histogram, TTree and TEventList are owned (by default) by the TFile
> object.
> In your case that means that once you do:
> TFolder* obj = (TFolder*)key->ReadObj(); // This line cause seg vio
> You 'own' the TFolder and you should delete it when your done with it.
> So you need to finish your function with:
> delete obj;
> to avoid the memory leak.
>
> Cheers,
> Philippe.
>
> PS. Note that in ROOT 4.00/08, instead of
> TKey *key = f->GetKey(k);
> TFolder* obj = (TFolder*)key->ReadObj();
> you can do
> TKey *key = f->GetKey(k);
> TFolder* obj = (TFolder*)key->ReadObj(TFolder::Class());
> where obj will be set to NULL if there is an object with
> the requested name but this object is not a TFolder.
>
> Better yet, you could use:
> TFolder *obj; f->GetObject(k,obj);
> where obj will be set to NULL if there is an object with
> the requested name but this object is not a TFolder.
>
> -----Original Message-----
> From: owner-about-root_at_listserv.fnal.gov
> [mailto:owner-about-root_at_listserv.fnal.gov] On Behalf Of Rob Snihur
> Sent: Thursday, March 17, 2005 9:03 PM
> To: about-root_at_fnal.gov; roottalk_at_root.cern.ch
> Subject: ReadObj memory leak?
>
> Hi,
> I am encountering a potential memory leak
> associated with the ReadObj command.
> Briefly, I am attempting to open a file
> which contains histograms, and access
> the pointer to a particular histogram.
> The file structure contains a key which
> is a TFolder (called "Ana") at the top level,
> and contains many sub-folders,
> ultimately containing histograms.
> The histogram file (~2 MB) and root macros are available at:
> http://www-cdf.fnal.gov/~snihur/root_leak/
> or directly at
> fcdflnx4.fnal.gov:/cdf/home/snihur/public_html/root_leak
>
> I show two simple macros below (m1 calls m2)
> which illustrate the problem. As I iterate,
> I can see memory consumption growing
> (with the "top" command),
> and I finally get a memory error.
> The only time I allocate memory,
> I believe that I delete it as well.
> Where is the memory leak?
>
> I am using root 4.00/08 in the CDF environment
> (what I get after I do
> "source ~cdfsoft/cdf2.cshrc; setup cdfsoft2 development").
> I also see a similar error in root 3.05/07
> (under "setup cdfsoft2 5.3.3").
>
> thanks,
> -rob
>
> fcdflnx4 501% cd public_html/root_leak/
> /cdf/home/snihur/public_html/root_leak
> fcdflnx4 502% cat m1.C
> #include "m2.C";
> void m1(int istart=0, int iend=10)
> {
> for(int i=istart;i<iend;i++) {
> cout << "i=" << i << endl;
> Int_t h =
> m2("test.root","JetProbBlockGenpBlock0/Hist/JetProbBlockGenpBlock0_JppPos","
> Ana");
>
> }
> }
> fcdflnx4 503% cat m2.C
> #include <iostream.h>
> #include <TFile.h>
> #include <TH1.h>
> #include <TFolder.h>
> #include <TKey.h>
> #include <TObject.h>
>
> Int_t m2(const Char_t *fname, const Char_t *hname, const Char_t *k)
> {
> TH1::AddDirectory(kFALSE);
> TFile *f = new TFile(fname); // Open file on heap.
> if ( f == 0 ) {
> cout << "Failed" << endl;
> return 0;
> }
> TKey *key = f->GetKey(k);
> TFolder* obj = (TFolder*)key->ReadObj(); // This line cause seg vio
> //TObject* obj1 = obj->FindObject(hname);
> //TH1F *h = (TH1F*)obj1;
> if ( f != NULL ) delete f;
> return 0;
> }
> fcdflnx4 504% setup cdfsoft2 development
> fcdflnx4 505% which root
> /home/cdfsoft/products/root/v4_00_08gGCC_3_4_3/Linux+2.4/bin/root
> fcdflnx4 506% root
> *******************************************
> * *
> * W E L C O M E to R O O T *
> * *
> * Version 4.00/08 1 December 2004 *
> * *
> * You are welcome to visit our Web site *
> * http://root.cern.ch *
> * *
> *******************************************
>
> FreeType Engine v2.1.3 used to render TrueType fonts.
> Compiled for linux with thread support.
>
> CINT/ROOT C/C++ Interpreter version 5.15.138, May 23 2004
> Type ? for help. Commands must be C++ statements.
> Enclose multiple statements between { }.
> root [0] TFile f("test.root");
> root [1] f.ls();
> TFile** test.root
> TFile* test.root
> KEY: TFolder Ana;1 StnAna folder
> root [2] .q
> fcdflnx4 507% root -l
> root [0] .x m1.C(1,10)
> i=1
> i=2
> i=3
> i=4
> i=5
> i=6
> i=7
> i=8
> terminate called after throwing an instance of 'std::bad_alloc'
> what(): St9bad_alloc
Received on Fri Mar 18 2005 - 08:09:11 MET