Task Execution - Java Concurrency in Practice - page 136

Writing such an Executor is trivial, as shown in ThreadPerTaskExecutor in Listing
6.5 .

Listing 6.5. Executor that Starts a New Thread for Each Task.

Similarly, it is also easy to write an Executor that would make TaskExecutionWe-
bServer behave like the single-threaded version, executing each task synchronously before
returning from execute , as shown in WithinThreadExecutor in Listing 6.6 .

6.2.2. Execution Policies

The value of decoupling submission from execution is that it lets you easily specify, and sub-
sequently change without great difficulty, the execution policy for a given class of tasks. An
execution policy specifies the “what, where, when, and how” of task execution, including:

Listing 6.6. Executor that Executes Tasks Synchronously in the Calling Thread.

• In what thread will tasks be executed?

• In what order should tasks be executed (FIFO, LIFO, priority order)?

• How many tasks may execute concurrently?

• How many tasks may be queued pending execution?