Execute Thread 2 only after Thread 1 finishes

Question

Would any of the following codes snippets give a guarantee that pool1 will start only after the pool finished its execution?

Snippet 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();
    }

Snippet 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();
    }

In snippet 1, I am prcessing as well as uploading images in multiple threads. In snippet 2, I am processing images in single thread and uploading them in multiple threds.

Answer 1

如果要在启动另一个任务之前等待一个或多个任务完成，则CountDownLatch通常很有用。