How to check the progress of a Process

Question

I have developed a standalone application using java, in which I am executing an external process using Runtime. But the execution of that process takes much time, and I would like to display a progress monitor of it.

How can I get the progress of a process that has been executed using Java runtime? Should I use a Progress Bar?

@Martinho No i do not control the code of the external process. — Antrromet, Feb 03 '11 at 11:42
Does the external process produce any easily identifiable side-effects as it runs (like, say, create some files at a certain point, or output some well-defined text)? — R. Martinho Fernandes, Feb 03 '11 at 11:45

score 4 · Accepted Answer · answered Feb 03 '11 at 11:40

To be able to 'know' the progress of the process, you will need to implement some sort of milestones that the process changes as it goes along. You will have to implement that logic so that the external process notifies your application of its progress. However, this is not always possible (because, first of all you need access to the code of the external process) or simple to do.

What you can do, is to use a Marquee Progress bar, this will keep an animation going indefinitevely:

Sometimes you can't immediately determine the length of a long-running task, or the task might stay stuck at the same state of completion for a long time. You can show work without measurable progress by putting the progress bar in indeterminate mode. A progress bar in indeterminate mode displays animation to indicate that work is occurring.

You can take a look at this Java tutorial (same place from where I got the above text) for more information.

God, I hate those. But sometimes they're the best we can get :( — R. Martinho Fernandes, Feb 03 '11 at 11:42
Yeah I know. I do not like them either, but they are better than not showing anything at all ;) — npinti, Feb 03 '11 at 12:01

score 1 · Answer 2 · answered Feb 03 '11 at 11:42

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You have to communicate with the external process to get its status. If the external process does not provide anything about its status, you could not accomplish what you want.

answered Feb 03 '11 at 11:42

Gursel Koca

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score 1 · Answer 3 · answered Feb 03 '11 at 11:43

This is only possible by reading from the process's output streams (myProcess.getInputStream() and myProcess.getErrorStream()), and of course only if the process displays its progress on the output.

There are processes that only display progress when they believe they are running in an interactive shell, so you have to "emulate" a shell by passing the corresponding environment parameters (wget is one of those tools).

Of course you have to manually parse the process's output.

If your external process includes piping data from one command to another, you can use the pv(1) command, to display the output.

score 1 · Answer 4 · answered Feb 03 '11 at 11:45

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To get to the core: if you do not know and can not control, measure or predict the duration of the transaction use jProgressBar1.setIndeterminate(true);

answered Feb 03 '11 at 11:45

Costis Aivalis

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Yes, but some users may take this as a sign that the application is not responding, and they will close the application, or, even worse, they may use Task Manager in Windows to kill the process, thus potentially damaging resources that the Java Virtual Machine is using. – Tech Expert Wizard Nov 22 '20 at 21:32

How to check the progress of a Process

4 Answers4