On 02/27/2014 09:22 AM, Paul Sandoz wrote:
On Feb 27, 2014, at 12:51 AM, Brian Burkhalter <brian.burkhal...@oracle.com>
wrote:
On Feb 26, 2014, at 1:53 PM, Paul Sandoz wrote:
Thanks for the suggestion, Paul. Assuming it is correct, in what way would this
be a better approach? (I apologize for being obtuse.)
IMHO it is a simpler solution. It's a cache line that requires updating not the
cache line*s*, as the current approach can potentially knock out cache lines
for other radixes.
Potentially yes, but not very likely, since the whole powerCache
reference is re-read again *after* the computation of cacheLine and then
replaced with a modified clone immediately after that. It should be
noted what Alan Eliasen already pointed-out in a discussion back in June
2013:
http://mail.openjdk.java.net/pipermail/core-libs-dev/2013-June/018375.html
...so I think what could be improved in current implementation is the
potential and more likely useless computation of the same values for the
same radix by multiple concurrent threads. Back then I presented an
alternative solution which solves that:
http://mail.openjdk.java.net/pipermail/core-libs-dev/2013-June/018457.html
...and as can be seen, does not use volatile read/write to publish
BigIntegers - that's why it is important that internal implementation of
such immutable classes like BigInteger is tolerant to unsafe publication...
Regards, Peter
I forgot to mention a slightly more complex variation is to CAS the cache line
instead of a lazy set, which can ensure a line does not knock another
containing a higher exponent.
Paul.
