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Is *this* really the best way to start a second JVM from Java code?

This is a followup to my own previous question and I’m kind of embarassed to ask this… But anyway: how would you start a second JVM from a standalone Java program in a system-independent way? And without relying on for instance an env variable like JAVA_HOME as that might point to a different JRE than the one that is currently running. I came up with the following code which actually works but feels just a little awkward:

public static void startSecondJVM() throws Exception {
    String separator = System.getProperty("file.separator");
    String classpath = System.getProperty("java.class.path");
    String path = System.getProperty("java.home")
                + separator + "bin" + separator + "java";
    ProcessBuilder processBuilder = 
                new ProcessBuilder(path, "-cp", 
    Process process = processBuilder.start();

Also, the currently running JVM might have been started with some other parameters (-D, -X…, …) that the second JVM would not know about.


It’s not clear to me that you would always want to use exactly the same parameters, classpath or whatever (especially -X kind of stuff – for example, why would the child need the same heap settings as its parents) when starting a secondary process.

I would prefer to use an external configuration of some sort to define these properties for the children. It’s a bit more work, but I think in the end you will need the flexibility.

To see the extent of possible configuration settings you might look at thye “Run Configurations” settings in Eclipse. Quite a few tabs worth of configuration there.