Request for review: 6761744 Hotspot crashes if process size limit is exceeded

[Thomas Schatzl]

Hi,

On Sun, 2013-04-07 at 22:22 -0700, Tao Mao wrote:
> 6761744 Hotspot crashes if process size limit is exceeded
> https://jbs.oracle.com/bugs/browse/JDK-6761744
>
> webrev:
> http://cr.openjdk.java.net/~tamao/6761744/webrev.00/
>
> changeset:
> The fix only needs to go to hsx24 since there's no perm gen in
> hotspot-25. Thus, the webrev is based on hsx24 repo.
>
> It provides for 32-bit builds a preventive check of the size of "the
> object heap + perm gen" before reserving VM memory. The total size
> should not exceed 4096MB (i.e. 4GB) for 32-bit builds; otherwise, the
> total doesn't make sense and, what's worse, overflow occurs. It will
> consequentially trigger anther error of memory access violation, which
> was not protected.

I think this check should be done once in Universe::reserve_heap() where
the actual reservation occurs, just before that if possible instead of
special handling for every collector.

Additionally, Universe::reserve_heap() also does final alignment before
reserving the heap which might influence the actually reserved heap
size.

Thomas