code: public void enableMmapIfSupported() {
  		if (validState) {
  			throw new InvalidStateException();
  		}
  		useMmap = Check64bitsJVM.JVMis64bits();
  		if (useMmap) {
  			log.info("Enabled mmap on 64bits JVM");
  		} else {
  			log.info("Disabled mmap on 32bits JVM");
  		}
  	}
docs: Enable mmap of files (default is not enabled) if JVM is 64bits, call before use {@link #open()}