in implicit threading Programmers identify threads

Run-time libraries (not programmers) create and manage threads

works well for tasks that are synchronous (cooperating).

works well for asynchronous (independent) tasks

in implicit threading Each task is mapped to a separate thread using the many-to-many model

At startup, the server creates a set of threads in a pool

Implicit fork-join is an asynchronous version of the thread pool

Create one or more child threads. then Wait for the created threads (children) to terminate. finally Join the threads, at which point it can retrieve and combine their results

When the server receives a request, it submits it to the pool

If the pool has a thread, the …. is served immediately

in Thread pool If the pool is empty, the task is queued until a thread becomes free

in Thread pool Once a thread completes serving the request, it returns to the pool.

…. can adjust the number of threads in the pool.

creating a thread is faster than Serving a request with an existing thread

Limiting the number of threads helps avoid exhausting system resources

Refers to terminating a thread before it has completed

Cancellation of a target thread can be asynchronous or deferred

The target thread periodically checks whether it should terminate

One thread immediately terminates the target thread

This allows the target thread to terminate itself in an orderly fashion