Question

Explain how asynchronous thread cancellation differs from deferred thread cancellation.

Answer 1

Thread cancellation is a process in which a thread is terminated prior to it's completion.For instance if there are multiple threads performing a search operation and one of those threads returns the result then the remaining threads can be terminated to optimize the performance of the system.

The thread which is to be cancelled is termed as the target thread.There are mainly two different cancellation methods

• Asynchronous Thread Cancellation :-

1. It is the process in which a the target thread is immediately terminated .
2. The thread gets abruptly terminated.
3. Cancellation of thread asynchronously may not free all the necessary resources allocated to that thread.
4. Asynchronous Cancellation can occur at any time.

• Deferred Thread Cancellation:-

1. It is a process in which the target thread periodically makes a check whether it should terminate itself.
2. It provides an opportunity so that the thread can be terminated in orderly fashion.
3. During Deferred Thread Cancellation a cleanup handler releases all the acquired resources of the thread before it is terminated.
4. Deferred Cancellation can occur only at defined points.