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Posted to dev@rocketmq.apache.org by GitBox <gi...@apache.org> on 2018/12/05 03:50:50 UTC

[GitHub] hutu92 opened a new issue #577: fix lastFlushTimestamp usage

hutu92 opened a new issue #577: fix lastFlushTimestamp usage
URL: https://github.com/apache/rocketmq/issues/577
 
 
   为了使问题描述的更加清楚，我就在此使用中文啦。
   
   FlushRealTimeService中`lastFlushTimestamp`的用法有一些问题，`lastFlushTimestamp`应该意味着**最后一次刷盘的时间**。FlushRealTimeService刷盘的逻辑应该是：当在`flushPhysicQueueThoroughInterval`时间区间内没有任何数据刷盘（意味着没有数据，或者待刷盘的数据不足`flushPhysicQueueLeastPages`个内存页），此时会执行一次完全刷盘，即将`flushPhysicQueueLeastPages`设置为0，无论多少数据都会刷盘。
   
   上述的逻辑参考CommitRealTimeService的实现。
   
   https://github.com/apache/rocketmq/blob/1bedba8cbcef32554d2dc80f2a340ea686d68ba9/store/src/main/java/org/apache/rocketmq/store/CommitLog.java#L971-L994
   
   很显然，上述代码并不符合此逻辑。
   
   此外，`mappedFileQueue.getStoreTimestamp`获取最后刷盘时间，获取的时间也不准确。因为在异步刷盘时，`flushPhysicQueueLeastPages`可能不为0，即使如果有数据刷盘了`storeTimestamp`也不会被及时更新。
   
   https://github.com/apache/rocketmq/blob/1bedba8cbcef32554d2dc80f2a340ea686d68ba9/store/src/main/java/org/apache/rocketmq/store/MappedFileQueue.java#L434-L436

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