GC statistics (was Re: big project ported)

[Godmar Back]

> 
> I would expect there to be an issue with the allocation of very large
> (multi-MB) Java arrays.  By default, and I believe the way they are
> allocated now, a misidentified pointer to anywhere in the array retains the
> array.  The allocator will try to place such arrays between known bogus
> references to minimize the problem.  But this tends to be hard for
> sufficiently big arrays.  I know of no way to avoid this issue without
> teaching the code generator to keep a reference to the beginning of the
> array around as long as the array is needed.  Once you do that, it becomes
> trivial.
> 

Hans,

in your 1996 PLDI paper [1], you discuss the problems with GC safety
that can occur if the code generator does not keep a reference to the
beginning of the array around and suggest an alternative to make
code GC-safe.

However, you said that "Such problems are in fact extremely rare with
existing compilers, ... and the above problems have only been observed
in examples contrived for the purpose"

Have things changed since or is this a different issue?

	- Godmar

[1] Boehm, H., ``Simple Garbage-Collector-Safety'', Proceedings 
of the ACM SIGPLAN '96 Conference on Programming Language Design 
and Implementation.