验证代码如下
ExecutorService executorService = Executors.newFixedThreadPool(3);
CompletableFuture a1 = CompletableFuture.supplyAsync(() -> {
logger.info("线程1{}{}","开始");
try {
TimeUnit.MILLISECONDS.sleep(100);
}catch (InterruptedException e) {
e.printStackTrace();
}
logger.info("线程1{}{}","结束");
return "1";
},executorService);
CompletableFuture a2 = CompletableFuture.supplyAsync(() -> {
logger.info("线程2{}{}","开始");
try {
TimeUnit.MILLISECONDS.sleep(100);
}catch (InterruptedException e) {
e.printStackTrace();
}
logger.info("线程2{}{}","结束");
return "1";
},executorService);
CompletableFuture a= a1.thenCombineAsync(a2,(s1,s2) -> {
logger.info("组合线程{}{}");
return s1+s2;
},executorService);
Object result = a.get();
当executorService线程池大小为2时候,执行结果如下:
[pool-4-thread-1] INFO test.rcd.thread.CompletableFutureDemo.lambda$mains$4:127 - 组合线程{}{}
a1.thenCombineAsync方法始终被线程1或2执行,
当executorService线程池大小为3时候,执行结果如下:
[pool-4-thread-3] INFO test.rcd.thread.CompletableFutureDemo.lambda$mains$4:127 - 组合线程{}{}
a1.thenCombineAsync方法始终被线程3执行,
改为a1.thenCombine(),执行结果:
a1.thenCombineAsync方法始终被线程1或2执行,
由此可见,async方法始终尝试取新线程执行方法,不带async方法则会从当前线程里取线程执行.CompletableFuture似是与线程无关的.
欢迎指教
