Can I call an arm64 Process using BuildProcess in Java?

Question

I am trying to call some terminal commands from Java using the Java ProcessBuilder with an M1 Mac that uses arm64. However, even though that I am using arm64 compatible JVM (Zulu 11, 17..) that identify arm64 chips, whenever I try to use the Java ProcessBuilder, it seems that the terminal is using Rosetta.

For example, the following command returns x86_64 instead of the expected arm64.

ProcessBuilder pb = new ProcessBuilder();
pb.command(new String[] {"bash", "-c", "uname -m"});
Process proc = pb.start();
BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(proc.getInputStream()));
String text = "";
String line;
while ((line = input.readLine()) != null) {
     text += line + System.lineSeparator();
}
bufferedReader.close();
System.out.println(text);

Do you know if there is any other way to execute terminal commands from Java using acutally the arm64 chip instead of the emulated Intel one?

Regards,

Carlos

Answer 1

By default, any process will inherit the architecture of the process that spawned it (if a slice for that architecture is available in the binary).

If the processes you're spawning from Java are running as x86_64, then that indicates that your Java process is running as x86_64, and if you did not explicitly invoke it as such, it further indicates that your shell, terminal, IDE or whatever you spawned it from, is also running as x86_64.

On the syscall layer, this behaviour can be overridden with Apple's proprietary posix_spawnattr_setbinpref_np() to select the preferred architecture slice in universal binaries when using posix_spawn().

On the command line, this is supported via the arch command:

arch -arm64 uname -m
arch -x86_64 uname -m

So in your code, this should look like this:

{"arch", "-arm64", "bash", "-c", "uname -m"}

You can also pass multiple architecture selectors to the arch command to be attempted in that order, so if you want your code to spawn native binaries whenever possible on either arm64 or x86_64 hosts, you can use:

{"arch", "-arm64", "-x86_64", "bash", "-c", "uname -m"}