[GitHub] xiangwangcheng opened a new issue #515: org.apache.rocketmq.common.stats.StatsItemSet#getAndCreateStatsItem has multi-thread problem

[GitBox <gi...@apache.org>]

xiangwangcheng opened a new issue #515: org.apache.rocketmq.common.stats.StatsItemSet#getAndCreateStatsItem has multi-thread problem
URL: https://github.com/apache/rocketmq/issues/515
 
 
   The code below
   ```
       public StatsItem getAndCreateStatsItem(final String statsKey) {
           StatsItem statsItem = this.statsItemTable.get(statsKey);
           if (null == statsItem) {
               statsItem = new StatsItem(this.statsName, statsKey, this.scheduledExecutorService, this.log);
               StatsItem prev = this.statsItemTable.put(statsKey, statsItem);
   
               if (null != prev) {
   
                   // statsItem.init();
               }
           }
   
           return statsItem;
       }
   ```
   has multi-thread problem. Because we can not ensure the atomicity of
   
   ```
   StatsItem statsItem = this.statsItemTable.get(statsKey);
   StatsItem prev = this.statsItemTable.put(statsKey, statsItem);
   ```
   Here is the test case. The result is not always the correct one 20000.
   
   ```
   public class BrokerStatsManagerTest {
   
       private BrokerStatsManager brokerStatsManager;
       private ThreadPoolExecutor executor;
       @Before
       public void init() {
           brokerStatsManager = new BrokerStatsManager("DefaultCluster");
           executor = new ThreadPoolExecutor(100, 200, 10, TimeUnit.SECONDS, new ArrayBlockingQueue<Runnable>(1000), new ThreadFactoryImpl("testMultiThread"));
       }
   
       @Test
       public void testBrokerStatsManager() throws InterruptedException {
   
           for(int i =0; i < 10000; i++) {
               executor.submit(new Runnable() {
                   @Override
                   public void run() {
                       brokerStatsManager.incTopicPutNums("topicTest", 2, 1);
                   }
               });
           }
           Thread.sleep(5000);
           System.out.println(brokerStatsManager.getStatsItem(TOPIC_PUT_NUMS,"topicTest").getValue());
       }
   }
   ```

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