JRuby - Prevent JVM from exiting

Question

I'm calling a method from an external library that includes System.exit(), shutting down the JVM when the method is called. Is there a way to prevent the JVM created through JRuby to run System.exit() if encountered?

I wouldn't expect anything good to come from ignoring `System.exit` — Elliott Frisch, Jul 06 '18 at 23:02
Possible duplicate of [Java: How to test methods that call System.exit()?](https://stackoverflow.com/questions/309396/java-how-to-test-methods-that-call-system-exit) — Jared Stewart, Jul 06 '18 at 23:18
The only real solution is to complain to the author(s) of that library that they shouldn't be using `System.exit(...)` — Mark Rotteveel, Jul 07 '18 at 12:48

score -1 · Accepted Answer · answered Jul 07 '18 at 12:01

you could install a SecurityManager for the JVM, using JRuby :

class SecurityManagerImpl < java.lang.SecurityManager

    def checkExit(status)
      raise java.lang.SecurityException.new("HALTED System.exit(#{status})") if status == 42
    end

    # optionally - disable all other checks from happening :
    superclass.instance_methods(false).select { |name| name.to_s.start_with?('check') }.each do |name|
      class_eval "def #{name}(*args) end" if name != :checkExit
    end

end

java.lang.System.setSecurityManager(SecurityManagerImpl.new)

now, all exit(42) calls will fail with a Java::JavaLang::SecurityException (HALTED System.exit(42)) which need to be handled up the call stack.

be aware that this is likely a very "hacky" work-around to have in place ...

JRuby - Prevent JVM from exiting

1 Answers1