Java ProcessBuilder to start multiple java processes

Question

Can I spawn multiple different JVMs given the same Main.class, arguments and VM options? Is it possible to do it with the ProcessBuilder?

Me too. I found some sample code here and there but nothing that actually worked :( — Virginia Woolf
– Virginia Woolf, Commented Dec 11, 2014 at 13:34
With "different JVM" do you mean multiple instances of the same JVM installation or a JVM 1.6, JVM 7, JVM 8, etc.? — Korashen
– Korashen, Commented Dec 11, 2014 at 13:46

fmodos · Accepted Answer · 2014-12-11 13:45:45Z

2

Here is a basic example using Process that starts 10 different JVM process:

   for (int i = 0; i < 10; i++) {
            new Thread(new Runnable() {

                public void run() {
                    try {
                        //start a new jvm with 256m of memory with the MyClass passing 2 parameters
                        String cmd = "java -Xmx256M -cp myjar.jar com.mymainclass.MyClass par1 par2";
                        Process p = Runtime.getRuntime().exec(cmd);
                        BufferedReader br = new BufferedReader(new InputStreamReader(p.getInputStream()));
                        String line = br.readLine();
                        while (line != null) {
                            line = br.readLine();
                        }
                        br = new BufferedReader(new InputStreamReader(p.getErrorStream()));
                        line = br.readLine();
                        while (line != null) {
                            line = br.readLine();
                        }
                    } catch (IOException e) {
                    }

                }
            }).start();
        }

answered Dec 11, 2014 at 13:45

fmodos

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3 Comments

Virginia Woolf Over a year ago

So I can't take advantage of the fact that I m doing all this from within the same jar in order not have to reference it this way and copy all environment parameters and arguments?

Gilberto Torrezan Over a year ago

You probally should use the Apache Commons Exec to prevent common mistakes when executing external processes from Java.

fmodos Over a year ago

@KaterinaA. the process is a clean new environment, it wont use anything of the current environment... this is the same with you open a prompt and enter de command

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