Parallel mark

The goal of parallel mark is to increase typical mark performance on a multiprocessor system, while not degrading mark performance on a uniprocessor system.

The performance of object marking is increased through the addition of helper threads that share the use of the pool of work packets. For example, full output packets that are returned to the pool by one thread can be picked up as new input packets by another thread.

Parallel mark still requires the participation of one application thread that is used as the coordinating agent. The helper threads assist both in the identification of the root pointers for the collection and in the tracing of these roots. Mark bits are updated by using host machine atomic primitives that require no additional lock.

For information about the number of helper threads that are created, and how you can change that number, see Frequently asked questions about the Garbage Collector.