see http://blog2.vorburger.ch/2014/01/eclipse-emf-xtext-memory-consumption-in.html

LoadAllModelsTest.java

package ch.vorburger.xtext.utils;

import java.io.File;
import java.util.Collection;

import org.apache.commons.io.FileUtils;
import org.eclipse.emf.common.util.URI;
import org.eclipse.emf.ecore.resource.Resource;
import org.eclipse.emf.ecore.resource.ResourceSet;
import org.eclipse.emf.ecore.resource.impl.ResourceSetImpl;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.odcgroup.workbench.core.helper.Timer;

public class LoadAllModelsTest {
	private static final Logger logger = LoggerFactory.getLogger(LoadAllModelsTest.class);

	public static void main(String[] args) {
		logMemory();
		Timer t = new Timer();
		
		t.start();
		File modelsRootDir = new File("...directory where your models are...");
		Collection<File> allModelFiles = FileUtils.listFiles(modelsRootDir, new String[] { "domain", "version", "enquiry", "rim", "eson", "menu" }, true);
		logger.info(allModelFiles.size() + " models found in " + modelsRootDir.toString());
		logger.info("Scanning directory took " + t.stopAndText());
		
		t.start();
		// ....
		// HERE YOU MUST DO THE *StandaloneSetup() of your respective Xtext-based language(s) 
		// ....
		logger.info("*StandaloneSetup took " + t.stopAndText());
		logMemory();
		
		// TODO look into IResourceLoader.. ParallelResourceLoader? :)
		
		t.start();
		ResourceSet rs = new ResourceSetImpl();
		int i = 1;
		for (File file : allModelFiles) {
			logger.info(i++ + ". loading " + file.toString());
			URI uri = URI.createFileURI(file.getAbsolutePath());
			Resource resource = rs.getResource(uri, true);
			if (resource == null || !resource.isLoaded() && resource.getContents().isEmpty())
				logger.warn("oups, resource == null or !loaded or isEmpty for URI: " + uri.toString());
			new NodesZapper().removeNodeModel(resource);
		}
		logger.info("Total getResource() took " + t.stopAndText());
		logMemory();
		
		logger.info("System.gc() ...");
		System.gc();
		logMemory();
	}

	private static void logMemory() {
		Timer gcTime = new Timer().start();
		System.gc();
		gcTime.stop();
		
		final int mb = 1024*1024;
		Runtime runtime = Runtime.getRuntime();
		
		long used = (runtime.totalMemory() - runtime.freeMemory()) / mb;
		long free = runtime.freeMemory() / mb;
		long total = runtime.totalMemory() / mb;
		long max = runtime.maxMemory() / mb;
		
		logger.info("After GC (which took {}), used: {} MB, free: {} MB, total: {} MB, max: {} MB", new Object[] { gcTime.text(), used, free, total, max });
	}	
}