java - 为什么 CompletableFuture.runAsync() 并不总是提交给 ForkJoinPool.commonPool()？

Question

CompletableFuture.runAsync 文档说明:

Returns a new CompletableFuture that is asynchronously completed by a task running in the ForkJoinPool.commonPool() after it runs the given action.

但是，据我所知，runAsync只向ForkJoinPool.commonPool()提交任务当ForkJoinPool.getCommonPoolParallelism() > 1 。如果没有，它会手动创建一个新的 Thread对于每个提交的任务。

为什么会出现这种情况？

Answer 1

是的，如果 ForkJoinPool 并行度小于 2，则为每个任务创建新线程 here

All async methods without an explicit Executor argument are performed using the ForkJoinPool.commonPool() (unless it does not support a parallelism level of at least two, in which case, a new Thread is created to run each task).