如何在特定时间内运行Java程序？

Question

I want to run my program on a list of files. But a few files take much longer than expected time. So I want to kill the thread/process after the timeout period, and run the program on next file. Is there any easy way to do it? I'll be running only one thread at a time.

Edit1:

I am sorry I couldn't make it clear earlier. Here is the for loop code.

for (File file : files)
{
  //Perform operations. 

}

So a file is Java program file which can contain many methods. If the number of methods are less, my analysis works fine. If there are many say 20 methods, it keeps executing and analyzing them for a few hours. So in the latter case, I would like to finish that execution and go for the next java file.

And I don't have any constraint of single threading. If multi-threading works, it's still good for me. Thanks.

Answer 1

These kinds of things are usually done multi-threaded. For an example, see How to timeout a thread .

As you commented though, you are looking for a single-threaded solution. That is best done by periodically checking if the timeout expired yet. Some thread will have to do the checking, and since you requested it to have only one thread, the checking will have to be somewhere halfway in the code.

Let's say that the majority of the time spent is in a while-loop that reads the file line-by-line. You could do something like this:

long start = System.nanoTime();
while((line = br.readLine()) != null) {
    if(System.nanoTime() - start > 600E9) { //More than 10 minutes past the start.
        throw new Exception("Timeout!");
    }
    ... //Process the line.
}

Answer 2

Just as a quick example of how you would do this using multi-threading:

First we make a Runnable for processing the File

class ProcessFile implements Runnable {
    File file;
    public ProcessFile(File file){
        this.file = file;
    }
    public void run(){
        //process the file here
    }
}

Next we actually execute that class as a thread:

class FilesProcessor {

    public void processFiles(){
        //I guess you get the files somewhere in here
        ExecutorService executor = Executors.newSingleThreadExecutor();
        ProcessFile process;
        Future future;
        for (File file : files) {
            process = new ProcessFile(file);
            future = executor.submit(process);
            try {
                future.get(10, TimeUnit.MINUTES);
                System.out.println("completed file");
            } catch (TimeoutException e) {
                System.out.println("file processing timed out");
            }
        }
        executor.shutdownNow();
    }
}

So we iterate through each file and process it. If it takes longer than 10 minutes, we get a timeout exception and the thread dies. Easy as pie.

Answer 3

I think you have a while or for loop for processing these files what about reading a timer each loop turn.

You can measure how long you are processing data with:

 while(....){
       long start = System.currentTimeMillis();
        // ... the code being measured ...    
        long elapsedTime = System.currentTimeMillis() - start;
 }

Or maybe starting chronometer before loop i don't know

EDIT : So if you have one loop turn by file you have to put somme time measure at some specific point in your code like said darius.

For example :

   for each file
           start = System.currentTimeMillis();
           //do some treatment
           elapsedTime = System.currentTimeMillis() - start;
           // do a more tratment
           elapsedTime = System.currentTimeMillis() - start;