RFR(XS) 8037959: BitMap::resize frees old map before copying memory if !in_resource_area

Mikael Gerdin mikael.gerdin at oracle.com
Wed Mar 26 11:25:21 UTC 2014

Hi Thomas,

On Wednesday 26 March 2014 12.01.02 Thomas Schatzl wrote:
> Hi Mikael,
> On Wed, 2014-03-26 at 11:03 +0100, Mikael Gerdin wrote:
> > Hi,
> > 
> > I've come up with a solution where I add a reallocate() method to
> > ArrayAllocator and have BitMap use that for growing its backing memory.
> > 
> > New webrev at: http://cr.openjdk.java.net/~mgerdin/8037959/webrev.1
>   looks okay, two minor nits:
> - in the test testResizeNonResource(), is it possible to set the
> ArrayAllocatorMallocLimit in both cases? Command line flags may set that
> to a value that makes the first test equal to the second.

Good point, that way I can make sure that I hit both paths in ArrayAllocator.

> - ArrayAllocator::reallocate should verify that this is indeed a
> reallocation and not called incorrectly, i.e. _addr is non-NULL.

I was attempting to follow the way libc realloc(ptr, sz) works, if you pass 
ptr as null it degenerates to a malloc(sz).

If I change it to a "pure" realloc I would need to change BitMap to keep track 
of its previous allocations or ask ArrayAllocator if anything is already 
allocated as well since the call from BitMap's constructor to resize is also 
the only way in which BitMap allocates memory.


> Thanks,
>   Thomas

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