JDK 9 RFR of JDK-8035279: Clean up internal deprecations in BigInteger

Brian Burkhalter brian.burkhalter at oracle.com
Wed Feb 26 19:51:17 UTC 2014

On Feb 26, 2014, at 4:56 AM, Peter Levart wrote:

>>> Not sure the static powerCache field, in the original code, needs to be volatile either:
>>> 1137     private static volatile BigInteger[][] powerCache;
>> Is there consensus on whether "volatile" is necessary here?
> I think it has to be volatile. The powerCache implementation was added in the following changeset:
>    http://hg.openjdk.java.net/jdk9/dev/jdk/rev/7546
> ...and improved later in the following:
>    http://hg.openjdk.java.net/jdk9/dev/jdk/rev/7586
> It uses a copy-on-write technique to extend the cache with new values when needed. volatile is mandatory here to safely publish the newly constructed array-of-arrays and the newly constructed sub-array to other threads. Without volatile, other threads could see null slots where BigInteger[] and/or BigInteger objects should be...

Thanks for the clarification, Peter.


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