UnsafeAtomicityTest crashes on SPARC
Alan.Burlison at oracle.com
Wed Aug 31 12:42:39 UTC 2016
On 30/08/2016 11:38, David Holmes wrote:
>> We have removed "&& info->si_code == BUS_OBJERR" in our JVM. It should
>> also catch other types like BUS_ADRALN.
> I'm not yet convinced that we should be anticipating/supporting
> unaligned access from Unsafe. But I'll look into this more closely later
> this week.
Hadoop makes misaligned accesses using Unsafe all over the place.
That's because the relevant Hadoop code is a pile and assumes it will
only ever run on architectures that support misaligned accesses. As it
is using Unsafe to do so there is a case to be made that they are
getting what they deserve, but on the other hand it means that they've
created a Java app that will not run on all the platforms that Java
I know Unsafe is going away, I don't know if the replacement will
prevent or allow similar misaligned accesses.
It might be useful if there was a run-time check that you could turn on
that checked for misaligned accesses, that way people writing such code
would at least have some way of figuring out if they have shot
themselves in the foot with regards to cross-platform portability.
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