google-app-engine - 谷歌应用引擎 : Unit testing concurrent access to memcache

Question

你们能告诉我一种在 Google App Engine 上模拟并发访问内存缓存的方法吗？我正在尝试使用 LocalServiceTestHelpers 和线程，但没有任何运气。每次我尝试在线程中访问 Memcache 时，都会收到此错误:

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

我猜GAE SDK的测试库试图模拟真实环境，因此只为一个线程(运行测试的线程)设置环境，其他线程看不到。

这里有一段代码可以重现问题

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));
 }
}

Answer 1

您是要测试您的应用程序还是 App Engine 的内存缓存实现？并发读取和写入下的内存缓存语义很好理解 - 您最好模拟可能发生的情况，以验证您的应用程序是否能够很好地处理这些情况。