Re: GTK free function doesn't appear to have any affect.

[dE <de techno gmail com>]

On 06/16/13 21:35, Chris Vine wrote:
> On Sun, 16 Jun 2013 12:28:52 +0530
> dE <de techno gmail com> wrote:
> > Apart from that, in the free_ptr? Does memory get freed for anyone
> > else?
> >
> > #include <stdio.h>
> > #include <gtk/gtk.h>
> > #define COLS 200
> > void free_ptr ( GtkListStore * );
> >
> > int main (  ) {
> >       gtk_init( NULL, NULL );
> >       int i, j;
> >       char *temp;
> >       GtkTreeIter current;
> >       GType *str_type = g_malloc (sizeof (GType) * COLS);
> >       for (i = 0; i < COLS; i++)
> >           str_type [i] = G_TYPE_STRING;
> >       GtkListStore *store = gtk_list_store_newv (COLS, str_type);
> >       g_free (str_type);
> >       for (i = 0; i < 300000 ; i++) {
> >           gtk_list_store_append ( store, &current );
> >           for ( j = 0 ; j < COLS ; j++ ) {
> >               gtk_list_store_set ( store , &current , j , "Hello world
> > Hello world Hello world!", -1 );
> >           }
> >       }
> >       printf ( "freeing after 10 seconds\n" );
> >       sleep (10);
> >       free_ptr ( store );
> >       printf ("Now freed\n");
> >       sleep (10);
> >       return 0;
> > }
> >
> > void free_ptr ( GtkListStore *store ) {
> >       gtk_list_store_clear (store);
> >       g_object_unref( G_OBJECT (store) );
> > }
> You should compile your code with warnings enabled.  Then you would
> find out other things about your code (namely that 'temp' is not used).
> Apart from that, technically the code is OK and it does destroy the
> list store correctly.
>
> Turning to the main point, the thing about your code is that it is
> inadequate for detecting memory leakage, because it does not take
> account of caching.  To come up with a meaningful test, you need to
> rerun the memory-using code more than once in the program.  If you do
> so, you will find that on each run other than the first, memory usage
> does not increase.  From this I deduce (I hope) that list stores cache
> the memory allocated to individual records for reuse. Presumably that
> is thought to be an optimization for most uses.  In the pathological
> case of a list store with 300000 x 300 cells holding allocated strings
> that clearly is not the case, but a list store with so many cells would
> be unusably slow anyway when used in conjunction with a tree view.
>
> There are various additional things you can do to check memory usage:
> see https://developer.gnome.org/glib/2.36/glib-running.html .
>
> For those kinds of pathological cases, you probably need to write your
> own tree model which does things the way you want them.
>
> Chris

Yes, I've realized in the main program that once memory is consumed, it 
does not increase after the table is reloaded; however I filled the 
memory till the peak (=physical ram + some of swap), it still doesn't 
free for 10 seconds at least.

I'm running the link you provided. Thank you!