Is "Concurrent execution of chunks" supported restart?

[wordywordy]

In the Spring Batch feature documentation, it mentions:
# Concurrent execution of chunks (a chunk is a batch of items processed in the same transaction) through the Spring TaskExecutor abstraction.

I think it refers that we can use some sort of 'async' taskexecutor to achieve the concurrent execution purpose. As far as I know, readers / writers are using some sort of 'marker' to support restart. This strategy require the items are in deterministic size and order. If the chunks are executed in parallel, will the 'restart' become unsupported?

[wordywordy]

Thanks in advance.

[chudak]

I'm using an async task executor and my batch is restartable (I've verified it). I'm not sure if chunks are processed concurrently or how that is handled internally.