java - 为什么ffmpeg的批处理会卡住系统？

Question

我需要从 50 多个 mp4 源文件中分割出更小的视频 block ，以获得 5000 多个记录。每条记录可能会从这 50 多个源文件中产生 2 或 3 个较小的 block 。

确定要选取哪个源文件的逻辑是用 Java 编写的，然后馈送到 ffmpeg上Runtime.getRuntime().exec()使用ExecutorService与 newFixedThreadPool如下:

private static boolean processqueue(ArrayList<String> cmds) {
    final ExecutorService pool;
    int threadsnum = Runtime.getRuntime().availableProcessors()-2;
    pool = Executors.newFixedThreadPool(threadsnum);

    for(final String cmd: cmds){ 
        pool.execute(new Runnable() {
            public void run() {
                System.out.println(cmd);
                try {
                    Runtime.getRuntime().exec(cmd);
                } catch (IOException e) {
                    e.printStackTrace();
                    pool.shutdown();
                }
            }
        });
    }                   
    pool.shutdown();

    // wait for them to finish for up to one minute.
    try {
        if(!pool.awaitTermination(1, TimeUnit.MINUTES)) {
            pool.shutdownNow();
        }

        //Wait a while for tasks to respond to being cancelled
        if(!pool.awaitTermination(1, TimeUnit.MINUTES))
            System.err.println("Pool did not shutdown properly");

    } catch (InterruptedException e) {
        e.printStackTrace();
        pool.shutdownNow();
        //Preserve interrupt status
        Thread.currentThread().interrupt();
        return false;
    }                   

    return true;
}

字符串cmd值是基于拆分或合并要求的其中之一:

对于分割:

ffmpeg -y -ss 00:00:00 -t 00:08 -i E:/tmp/fin12.mp4 -acodec copy -vcodec copy E:/tmp/Intermed/0136f.mp4

或

合并:

ffmpeg -y -i E:/tmp/Inter/0136c0.mp4 -i E:/tmp/Inter/0136c1.mp4 -i E:/tmp/Inter/0136f.mp4 -i E:/tmp/Jingle.mp4 -i E:/tmp/wm1280.png -filter_complex "[0:v][0:a][1:v][1:a][2:v][2:a][3:v][3:a]concat=n=4:v=1:a=1[vv][a];[vv][4:v]overlay=x=0:y=H-overlay_h[v]" -map "[v]" -map "[a]" E:/tmp/final/0136.mp4

第一次尝试时，仅处理了 250 条记录。并且，在随后尝试处理余额记录时，它抛出了以下异常；但是，又处理了 300 条记录:

java.io.IOException: Cannot run program "ffmpeg": CreateProcess error=1455, The paging file is too small for this operation to complete
at java.lang.ProcessBuilder.start(Unknown Source)

并且，此代码经常卡住。为什么是ExecutorService没有等待队列来处理所有记录并优雅地退出？我做错了什么？

注意:我通过传递从命令行执行的相关参数来从 Windows 批处理脚本调用 Java 类。

Answer 1

您正在开始执行，但不等待它完成，因此您的线程池只会启动与命令一样多的进程。我不确定你的其余 try/catch 正在尝试做什么。我建议你使用 CountdownLatch。这是一个例子:

public static void main(String[] args) {
    List<String> cmds = Lists.newArrayList("sleep 1", "sleep 2", "sleep 3");

    final ExecutorService pool;
    int threadsnum = Runtime.getRuntime().availableProcessors() - 2;
    pool = Executors.newFixedThreadPool(threadsnum);


    CountDownLatch latch = new CountDownLatch(cmds.size());


    for (final String cmd : cmds) {
        pool.submit(() -> {
            try {
                System.out.println("to be executed: " + cmd);
                Runtime.getRuntime().exec(cmd).waitFor();
                latch.countDown();
            }
            catch (IOException e) {
                Thread.currentThread().interrupt();
            }
            catch (InterruptedException e) {
                e.printStackTrace();
            }
        });

    }

    try {
        latch.await(10, TimeUnit.SECONDS);
        if (latch.getCount() > 0) {
            System.out.println("Waited long enough. There are " + latch.getCount() + " threads still running");
        }
    }
    catch (InterruptedException e) {
        e.printStackTrace();
    }
    finally {
        pool.shutdown();
    }
    System.out.println("Completed.");

}