RFR (XXS): 8075288: malloc without free in VM_PopulateDumpSharedSpace::doit()

Jungwoo Ha jwha at google.com
Fri Apr 10 13:31:42 UTC 2015


What's the conclusion? Should I fix it or discuss it separately?

On Thu, Apr 9, 2015 at 2:43 PM, Kim Barrett <kim.barrett at oracle.com> wrote:

> On Apr 9, 2015, at 1:25 PM, Jungwoo Ha <jwha at google.com> wrote:
> >
> > Can someone sponsor this change?
> >
> > https://bugs.openjdk.java.net/browse/JDK-8075288
> > http://cr.openjdk.java.net/~jwha/8075288/webrev.00
>
> I think the change is correct.  Good find!
>
> However, it’s not clear to me why this is using malloc (and now free),
> rather than stack allocation.
> The size is a declared variable at the allocation point, but it’s
> initialized from a constant with a
> not big value (17) and never modified, so could be changed to be a
> constant.
>
> That is, instead of
>
>  592   char* saved_vtbl = (char*)os::malloc(vtbl_list_size *
> sizeof(void*), mtClass);
>  593   memmove(saved_vtbl, vtbl_list, vtbl_list_size * sizeof(void*));
>
> use
>
>   void* saved_vtbl[vtbl_list_size];
>   memmove(saved_vtbl, vtbl_list, ARRAY_SIZE(saved_vtbl));
>
> Maybe the worry is that vtbl_list_size might not always be a small
> constant?
>
> Probably this question of whether to use malloc/free here at all should be
> a separate CR.
>
>
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