Re: [Vala] Help with Memory Leak

[Evan Nemerson <evan coeus-group com>]

On Fri, 2012-07-06 at 14:27 -0400, Bruce Reidenbach wrote:
> Hello all,
>
> I am encountering a memory leak in an appindicator menu. The menu is made
> up of several RadioMenuItems that have their labels updated once per
> second.  I have tracked the memory leak down to the following code, but
> cannot seem to be able to make any additional headway.  The method "update"
> is called from several sources, and specifies the radio item and the values
> to update via a const array of FORMAT statements.  If I comment out the
> code that sets the radio menu item label and un-comment the printf
> statement, the leak disappears.  The leak is minor -- on the order of about
> 20 to 30 bytes per invocation -- but over time it adds up.
>
> I'm not sure if this is the correct forum for asking for help, or whether
> this is a problem with the gtk+-3.0 or appindicator3-0.1 packages, but I
> thought I'd see if anyone has any ideas in the Vala community first.
>
> Thanks,
> Bruce
>
> //
> -------------------------------------------------------------------------------------
> //  Make results more readable by appending the appropriate metric unit to
> the data
> //
> -------------------------------------------------------------------------------------
>
>   private const string suffix [] = { "bytes", "KiB", "MiB", "GiB", "TiB",
> "PiB", "EiB", "ZiB" };
>
>   private string readable (float bytes) {
>     foreach (string s in suffix) {
>       if (bytes < 1024.0) {
>         var format = (s == "bytes") ? "%.0f %s" : "%.1f %s";
>         return format.printf (bytes, s);
>       }
>       bytes = bytes / 1024.0f;
>     }
>     return "%.1f YiB".printf (bytes);
>   }
>
> //
> -------------------------------------------------------------------------------------
> //  Menu update
> //
> -------------------------------------------------------------------------------------
>
>   public void update (int item, float pct, float val1, float? val2 = 0.0f) {
>     var text = (item == 0) ? FORMAT [item].printf (val1)
>                            : FORMAT [item].printf (readable (val1),
> readable (val2));
>     radioItem [item].label = (owned) text;   //  **** Leaky? ****

Get rid of (owned).  That is used to transfer ownership of a reference,
but g_menu_item_set_label doesn't steal the reference you pass it, so
what ends up happening here is that GTK+ will copy the string you pass
it, and since you told Vala that you want to transfer ownership it will
not free the string when it goes out of scope, and you end up leaking
it.


-Evan