Tuesday, November 22, 2011

GCC 4.7.0: transactional memory

Eventually GCC 4.7.0 will have transactional memory, which has been
merged several days ago. Draft of still-in-progress design document can
be found here.

In short, (atomic) transaction is something similar to this:

    __transaction_atomic { x++; }
Any operation performed within the __transaction_atomic block will be atomic and
isolated from other transactions, operations within __transaction {} either be visible to other threads in its entirety or not at all.

Quote from lwn
Details on the specific implementation are scarce; it appears that, in the current patch set,
transactions will be implemented using a global lock. GCC developers debated for a bit over
whether this code was ready for merging or not. In the end, though, the possibility of being
the first to support an interesting new feature seemed to win out. Current plans are to
release 4.7.0 sometime around next April.

Refer to gcc.gnu.org (or gcc 4.7 svn repository) for details.

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