what do these lines means in servlet 3.0 specification ?

[gurpeet singh]

Hi Everybody,

i have started with servlet 3.0 specification and currently on the topic of asynchronous processing. i'm unable to understand the following piece of line . the below lines can be found at section 2.3.3.3 Asynchronous Processing , page 11

The application is responsible to handle concurrent access to the request and response
objects if the async task is executing before the container-initiated dispatch that
called startAsync has returned to the container.

i'm not able to understand what do the lines " if the aysnc task is executing.......has returned to the container " means ?

Thanks