Demonstrating the effect of JVM arg -XX:-MaxFDLimit on OSX

demo.sh

$ cat /Library/LaunchDaemons/limit.maxfiles.plist
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
  <dict>
    <key>Label</key>
      <string>limit.maxfiles</string>
    <key>ProgramArguments</key>
      <array>
        <string>launchctl</string>
        <string>limit</string>
        <string>maxfiles</string>
        <string>524288</string>
        <string>524288</string>
      </array>
    <key>RunAtLoad</key>
      <true/>
    <key>ServiceIPC</key>
      <false/>
  </dict>
</plist>
$ ulimit -n ; ulimit -Hn
524288
524288
$ java -version
openjdk version "1.8.0_222"
OpenJDK Runtime Environment (AdoptOpenJDK)(build 1.8.0_222-b10)
OpenJDK 64-Bit Server VM (AdoptOpenJDK)(build 25.222-b10, mixed mode)
$ cat Fds.java 
import com.sun.management.UnixOperatingSystemMXBean;
import java.lang.management.ManagementFactory;

public class Fds {
    public static void main(final String[] argv) {
        final UnixOperatingSystemMXBean osMBean =
            (UnixOperatingSystemMXBean) ManagementFactory.getOperatingSystemMXBean();
        System.out.println("opendfs: " + osMBean.getOpenFileDescriptorCount());
        System.out.println("maxfds:  " + osMBean.getMaxFileDescriptorCount());
    }
}
$ javac Fds.java
$ java Fds
opendfs: 5
maxfds:  10240
$ java -XX:-MaxFDLimit Fds
opendfs: 5
maxfds:  524288