仅在线程 1 完成后执行线程 2

Question

以下任何代码片段是否可以保证 pool1 仅在池完成执行后才会启动？

片段 1

    ExecutorService pool = Executors.newFixedThreadPool(numberOfThreads);
    for (FObject action : list) {
        if (action instanceof FObject) {    
            Runnable run = new ImageProcessRunnable(action);
            pool.execute(run);
        }
    }
    pool.shutdown();
    if (pool.awaitTermination(10, TimeUnit.SECONDS)) {
        pool.shutdownNow();
    }           
    ExecutorService pool1 = Executors.newFixedThreadPool(numberOfThreads);
    synchronized (ImageHelper.getFilePaths()) {
        for (String file :ImageHelper.getFilePaths()) {
            pool1.execute(() -> {
                UploadFileAsAppUser.uploadFileAsBoxAppUser(file, boxLocation);
            });
        }
    }
    pool1.shutdown();
    if (pool1.awaitTermination(10, TimeUnit.SECONDS)) {
        pool1.shutdownNow();
    }

片段 2

    for (FObject action : list) {
        if (action instanceof FObject) {    
            ImageProcessor processor = new ImageProcessor();
        }
    }
    ExecutorService pool1 = Executors.newFixedThreadPool(numberOfThreads);
    synchronized (ImageHelper.getFilePaths()) {
        for (String file :ImageHelper.getFilePaths()) {
            pool1.execute(() -> {
                UploadFileAsAppUser.uploadFileAsBoxAppUser(file, boxLocation);
            });
        }
    }
    pool1.shutdown();
    if (pool1.awaitTermination(10, TimeUnit.SECONDS)) {
        pool1.shutdownNow();
    }

在片段 1 中，我正在练习并在多个线程中上传图像。在片段 2 中，我正在单线程中处理图像并以多个线程上传它们。

Answer 1

如果要

等待一个或多个任务完成，然后再开始另一个任务，则 CountDownLatch 通常很有用。