Java - Problems with reading from process output

Question

My OS is Windows 8.1 64 bit I need to read process output, but if it works more than 5 hours, I should destroy the process. So, there are two ways: 1) process works < 5 hours and it ends by itself; 2) it if works >= 5 hours, after that time I destroy it. I had two variants:

1.

ProcessBuilder pb = new ProcessBuilder(corePath.getAbsolutePath(), ... );
Process core = pb.start();
if(!core.waitFor(5, TimeUnit.HOURS))
{
    System.out.println("Process destroyed, path " + root.getAbsolutePath());
    core.destroy();
}
String output = IOUtils.toString(core.getInputStream());
return output;

2.

Process core = pb.start();
StringBuilder sb = new StringBuilder();
BufferedReader input = new BufferedReader(new InputStreamReader(core.getInputStream()));
String line;
while(System.currentTimeMillis() < end && (line = input.readLine()) != null)
{
    sb.append(line);
}
input.close();

Problems: 1) program was waiting exactly 5 hours (even if process should be finished in few seconds) 2) program is waiting until the process is end

May someone advise another way to handle this? Thanks

Chances are you need to do a bit of both: you need to have a thread that reads the standard output of the process (you can throw away the contents) and you need a thread that waits for the process to finish or 5 hours using Process.waitFor(). The reason for this is that with 1 the process might block, waiting for you to read out its output buffer, while with 2 your application will block, waiting indefinitely in input.readLine() until it outputs a line. — biziclop
– biziclop, Commented Jun 15, 2015 at 14:12

user4920910 · Accepted Answer · 2015-06-15 14:11:29Z

2

I think the problem may be with the BufferedReader. Are you trying to use the BufferedReader to get inptut? If so, use the Scanner class.

answered Jun 15, 2015 at 14:11

user4920910

Sign up to request clarification or add additional context in comments.

1 Comment

Kalle Richter Over a year ago

I could solve a deadlock because of BufferedReader.readLine or InputStreamReader.read blocking forever after the underlying process has been destroyed by reading with while(process.isAlive()) {while(scanner.hasNext()) {String line = scanner.nextLine();}} on different threads for both stdout and stderr.

Collectives™ on Stack Overflow

Java - Problems with reading from process output

1 Answer 1

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related