4-Concurrency Models

http://tutorials.jenkov.com/java-concurrency/concurrency-models.html

Parallel Workers

The parallel worker concurrency model is the most commonly used concurrency model in Java applications (although that is changing). Many of the concurrency utilities in the java.util.concurrent Java package are designed for use with this model.

In the parallel worker concurrency model a delegator distributes the incoming jobs to different workers. Each worker completes the full job. The workers work in parallel, running in different threads, and possibly on different CPUs.

Pros:

• The advantage of the parallel worker concurrency model is that it is easy to understand. To increase the parallelization of the application you just add more workers.

Cons:

• Shared State Can Get Complex-共享变量-复杂

• Job Ordering is Nondeterministic

Assembly Line

Functional Parallelism

The basic idea of functional parallelism is that you implement your program using function calls. Functions can be seen as "agents" or "actors" that send messages to each other, just like in the assembly line concurrency model (AKA reactive or event driven systems). When one function calls another, that is similar to sending a message.

All parameters passed to the function are copied, so no entity outside the receiving function can manipulate the data. This copying is essential to avoiding race conditions on the shared data.