| 33 |
|
* <p>A "main" {@code ForkJoinTask} begins execution when it is |
| 34 |
|
* explicitly submitted to a {@link ForkJoinPool}, or, if not already |
| 35 |
|
* engaged in a ForkJoin computation, commenced in the {@link |
| 36 |
< |
* ForkJoinPool#commonPool} via {@link #fork}, {@link #invoke}, or |
| 36 |
> |
* ForkJoinPool#commonPool()} via {@link #fork}, {@link #invoke}, or |
| 37 |
|
* related methods. Once started, it will usually in turn start other |
| 38 |
|
* subtasks. As indicated by the name of this class, many programs |
| 39 |
|
* using {@code ForkJoinTask} employ only methods {@link #fork} and |
| 55 |
|
* minimize other blocking synchronization apart from joining other |
| 56 |
|
* tasks or using synchronizers such as Phasers that are advertised to |
| 57 |
|
* cooperate with fork/join scheduling. Subdividable tasks should also |
| 58 |
< |
* not perform blocking IO, and should ideally access variables that |
| 58 |
> |
* not perform blocking I/O, and should ideally access variables that |
| 59 |
|
* are completely independent of those accessed by other running |
| 60 |
|
* tasks. These guidelines are loosely enforced by not permitting |
| 61 |
|
* checked exceptions such as {@code IOExceptions} to be |
| 73 |
|
* <p>It is possible to define and use ForkJoinTasks that may block, |
| 74 |
|
* but doing do requires three further considerations: (1) Completion |
| 75 |
|
* of few if any <em>other</em> tasks should be dependent on a task |
| 76 |
< |
* that blocks on external synchronization or IO. Event-style async |
| 76 |
> |
* that blocks on external synchronization or I/O. Event-style async |
| 77 |
|
* tasks that are never joined (for example, those subclassing {@link |
| 78 |
|
* CountedCompleter}) often fall into this category. (2) To minimize |
| 79 |
|
* resource impact, tasks should be small; ideally performing only the |
| 635 |
|
/** |
| 636 |
|
* Arranges to asynchronously execute this task in the pool the |
| 637 |
|
* current task is running in, if applicable, or using the {@link |
| 638 |
< |
* ForkJoinPool#commonPool} if not {@link #inForkJoinPool}. While |
| 638 |
> |
* ForkJoinPool#commonPool()} if not {@link #inForkJoinPool}. While |
| 639 |
|
* it is not necessarily enforced, it is a usage error to fork a |
| 640 |
|
* task more than once unless it has completed and been |
| 641 |
|
* reinitialized. Subsequent modifications to the state of this |
