[GitHub] Jason918 commented on a change in pull request #220: [ROCKETMQ-332] MappedFileQueue#findMappedFileByOffset is not thread safe, which will cause message loss.

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Jason918 commented on a change in pull request #220: [ROCKETMQ-332] MappedFileQueue#findMappedFileByOffset is not thread safe, which will cause message loss.
URL: https://github.com/apache/rocketmq/pull/220#discussion_r162038566
 
 

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 File path: store/src/main/java/org/apache/rocketmq/store/MappedFileQueue.java
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 @@ -461,26 +461,38 @@ public boolean commit(final int commitLeastPages) {
      */
     public MappedFile findMappedFileByOffset(final long offset, final boolean returnFirstOnNotFound) {
         try {
-            MappedFile mappedFile = this.getFirstMappedFile();
-            if (mappedFile != null) {
-                int index = (int) ((offset / this.mappedFileSize) - (mappedFile.getFileFromOffset() / this.mappedFileSize));
+            MappedFile firstMappedFile = this.getFirstMappedFile();
 
 Review comment:
    If the first mappedFile is deleted between line 464 and line 467, this method still returns null when the requested offset is in the last mappedFile( mappedFiles.size() is less than index).
   @zhouxinyu @dongeforever 

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