Would you guys show me a way to simulating concurrent access to memcache on Google App Engine? I'm trying with LocalServiceTestHelpers and threads but don't have any luck. Every time I try to access Memcache within a thread, then I get this error:

ApiProxy$CallNotFoundException: The API package 'memcache' or call 'Increment()' was not found

I guess that the testing library of GAE SDK tried to mimic the real environment and thus setup the environment for only one thread (the thread that running the test) which cannot be seen by other thread.

Here is a piece of code that can reproduce the problem

package org.seamoo.cache.memcacheImpl;

import org.testng.Assert;
import org.testng.annotations.AfterMethod;
import org.testng.annotations.BeforeMethod;
import org.testng.annotations.Test;

import com.google.appengine.api.memcache.MemcacheService;
import com.google.appengine.api.memcache.MemcacheServiceFactory;
import com.google.appengine.tools.development.testing.LocalMemcacheServiceTestConfig;
import com.google.appengine.tools.development.testing.LocalServiceTestHelper;

public class MemcacheTest {
 LocalServiceTestHelper helper;

 public MemcacheTest() {
  LocalMemcacheServiceTestConfig memcacheConfig = new LocalMemcacheServiceTestConfig();
  helper = new LocalServiceTestHelper(memcacheConfig);
 }

 /**
  * 
  */
 @BeforeMethod
 public void setUp() {
  helper.setUp();
 }

 /**
  * @see LocalServiceTest#tearDown()
  */
 @AfterMethod
 public void tearDown() {
  helper.tearDown();
 }

 @Test
 public void memcacheConcurrentAccess() throws InterruptedException {
  final MemcacheService service = MemcacheServiceFactory.getMemcacheService();
  Runnable runner = new Runnable() {

   @Override
   public void run() {
    // TODO Auto-generated method stub
    service.increment("test-key", 1L, 1L);
    try {
     Thread.sleep(200L);
    } catch (InterruptedException e) {
     // TODO Auto-generated catch block
     e.printStackTrace();
    }
    service.increment("test-key", 1L, 1L);
   }
  };

  Thread t1 = new Thread(runner);
  Thread t2 = new Thread(runner);
  t1.start();
  t2.start();
  while (t1.isAlive()) {
   Thread.sleep(100L);
  }
  Assert.assertEquals((Long) (service.get("test-key")), new Long(4L));
 }
}