Re: 971110: Memory leak question

>To: address@hidden
>From: address@hidden
>Subject: Memory leak question
>Organization: .
>Keywords: 199711101835.LAA26543

Hi John,

>    I've written some code in C++ that I can't seem to free up the memory 
>    after I've used nc_close().  All my code does is open a netCDF file and 
>    use a nc_get_var_short() to read in a 3D variable.  I then close the 
>    file with nc_close and wait for another file to be opened.  The memory 
>    allocated for the nc_get_var_short() is never returned.  I'm working on 
>    an SGI Octane running IRIX 6.3.  Am I just not closing the netCDF file 
>    properly or do I need to change over to the c version of netCDF. 

I can't duplicate the problem.  If you invoke the nc_close() member
function on the netCDF file before exiting, you are closing the file
properly.

I've run the appended test program using memory checking on a Solaris
2.6 system with netCDF 3.3.1, and it reports no memory leaks when the
program terminates.

We don't have access to an IRIX 6.3 system, but I've compiled and run
the program on an IRIX 6.2 system.  I tried to use the "purify" tool to
check for memory leaks, but our current copy of purify gets a
segmentation violation on this, so maybe it's not up to date.

There is a patch for a memory leak problem in the C++ code available
from our "Known Problems" page, at

  http://www.unidata.ucar.edu/packages/netcdf/known_problems.html#cxxleak

but I think it may be unrelated to the problem you are reporting.
Nevertheless, you might try that patch and see if it makes the symptoms
go away.

--Russ

_____________________________________________________________________

Russ Rew                                         UCAR Unidata Program
address@hidden                     http://www.unidata.ucar.edu

#include <stdio.h>
#include <stdlib.h>
#include "netcdf.hh"

NcFile *ncfile;

int main()
{
  short t0[] = { 0,  1,  2,  3,  4,  5,  6,  7,  8,   9, 10, 11,
                 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23};

    NcFile ofile = NcFile("jnk.nc", NcFile::Replace);
    ncfile = &ofile;
    if (!ofile.is_valid()){
      cerr << "invalid ofile\n";
      return(1);
    }

    NcDim* tdim = ofile.add_dim("time", 2);
    NcDim* lat = ofile.add_dim("lat", 3);
    NcDim* lon = ofile.add_dim("lon", 4);
    NcVar* tvar = ofile.add_var("temp", ncShort, tdim, lat, lon);

    if(!tvar->put(t0, 2, 3, 4))
        cerr << "put failed\n";

    ofile.close();

    NcFile nfile = NcFile("jnk.nc");
    NcVar* nvar = nfile.get_var("temp");
    short temp[2][3][4];

    if(!nvar->get(&temp[0][0][0], 2, 3, 4))
        cerr << "get failed\n";
    nfile.close();    
}