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ori2003
V2EX    Java

Java CompletableFuture 使用问题?大佬帮忙看看

  •  
  •   ori2003 2023-10-16 17:43:48 +08:00 1862 次点击
    这是一个创建于 801 天前的主题,其中的信息可能已经有所发展或是发生改变。

    正常 main 方法执行完之后会退出:Process finished with exit code 0

    但是我执行下边的代码,主线程阻塞了,为什么不退出呢? 执行结果如下:

    执行 step 1 主流程 0.5 完了 主流程完了 执行 step 2 step1 result , step2 result 执行 step 3 step3 rsult 

    代码在这里:

    public static void main(String[] args) { ExecutorService executor1 = Executors.newFixedThreadPool(5); CompletableFuture<String> cf1 = CompletableFuture.supplyAsync(() -> { System.out.println("执行 step 1"); return "step1 result"; }, executor1); CompletableFuture<String> cf2 = CompletableFuture.supplyAsync(() -> { try { Thread.sleep(1000); } catch (InterruptedException e) { throw new RuntimeException(e); } System.out.println("执行 step 2"); return "step2 result"; }, executor1); System.out.println("主流程 0.5 完了"); cf1.thenCombine(cf2, (result1, result2) -> { try { Thread.sleep(1000); } catch (InterruptedException e) { throw new RuntimeException(e); } System.out.println(result1 + " , " + result2); System.out.println("执行 step 3"); return "step3 result"; }).thenAccept(result3 -> System.out.println(result3)); System.out.println("主流程完了"); } 
    6 条回复    2023-10-17 09:40:12 +08:00
    Plutooo
        1
    Plutooo  
       2023-10-16 17:57:07 +08:00   6
    executor1 没有 shutdown
    admin7785
        2
    admin7785  
       2023-10-16 18:22:42 +08:00 via iPhone
    美团技术平台文章里的代码?他那个不完整
    https://mp.weixin.qq.com/s/GQGidprakfticYnbVYVYGQ
    seedscoder
        3
    seedscoder  
       2023-10-16 18:29:30 +08:00
    ```
    ExecutorService executor1 = Executors.newFixedThreadPool(5);
    ```

    创建出来的是非守护线程,所以程序没有退出?
    Edward4074
        4
    Edward4074  
       2023-10-16 19:50:46 +08:00
    最后加个 executor1.shutdown();
    wdf1286
        5
    wdf1286  
       2023-10-17 08:16:24 +08:00   1
    主线程没阻塞,jvm 不退出是因为还有非 daemon 线程活着
    ori2003
        6
    ori2003  
    OP
       2023-10-17 09:40:12 +08:00
    @wdf1286 是的,感谢
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