G1 GC: What is SATB buffer?

Question

In Java 8 G1 GC, what is SATB buffer?

I saw this term in: http://www.oracle.com/technetwork/articles/java/g1gc-1984535.html

After searching via Google, didn't found it's definition.

Any help? Thanks.

Answer 1

I assume it's a buffer for the

G1 GC uses the Snapshot-At-The-Beginning (SATB) algorithm, which takes a snapshot of the set of live objects in the heap at the start of a marking cycle.

http://xiao-feng.blogspot.co.uk/2007/04/incremental-update-tracing-vs-snapshot.html

https://rkennke.wordpress.com/2013/06/19/shenandoah-gc-concurrent-parallel-marking/

Answer 2

The document you are referring to says:

G1 GC uses the Snapshot-At-The-Beginning (SATB) algorithm, which takes a snapshot of the set of live objects in the heap at the start of a marking cycle.

So the logical conclusion would be: these buffers are used by that algorithm in order to store that snapshot.