Question

I have checked different questions in this and in other forums, but I didn’t find the solution to my problem.

I have an application which runs ffmpeg and exiftool processes. I have concurrency probles, and I would like to control them, using Thread. This is how I built it:

ExiftoolThread

public class ExiftoolThread extends Thread{

    String file;

    public ExiftoolThread(String file){
        this.file = file;
    }
     public void run(){
                serviceToExiftool(file);//Create metadata file
    }
}

FfmpegThread

public class FfmpegThread extends Thread{

    String itemName;

    public FfmpegThread(String itemName){
        this.itemName = itemName;
    }
     public void run(){
         serviceFFmpeg(itemName);//Create thumbnai froma  video
    }
}

Main call

Thread exiftoolThread = new ExiftoolThread(file.getName());
        exiftoolThread.run();
        try {
            exiftoolThread.join(3000);
        } catch (InterruptedException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        log.write("JSON file created.It contains the metadata. ");


            Thread ffmpegThread = new FfmpegThread(itemName);
            ffmpegThread.run();
            try {
                ffmpegThread.join(3000);
            } catch (InterruptedException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
            log.write("Thumbnail created successfully. ");

After this call finishes, there are more actions working with the results of these processes, and there is always one of them which is missed. I guess that’s because one of them (exiftool or ffmpeg) finishes earlier and then the process continue before the other finishes.

I am using ffmpegThread.join(3000); to skip this problem, as the documentation says, this method waits untill the thread is died. What am I missing?

Thanks in advance

Answer 1

You have to call start() to run the code in the new thread. Also, join() block the current thread, so you have to call it after you start all your thread.