[GitHub] [spark] cloud-fan commented on a change in pull request #31643: [SPARK-34534] Fix blockIds order when use FetchShuffleBlocks to fetch blocks

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

cloud-fan commented on a change in pull request #31643:
URL: https://github.com/apache/spark/pull/31643#discussion_r585359529



##########
File path: common/network-shuffle/src/main/java/org/apache/spark/network/shuffle/OneForOneBlockFetcher.java
##########
@@ -106,17 +107,17 @@ private boolean isShuffleBlocks(String[] blockIds) {
   }
 
   /**
-   * Analyze the pass in blockIds and create FetchShuffleBlocks message.
-   * The blockIds has been sorted by mapId and reduceId. It's produced in
-   * org.apache.spark.MapOutputTracker.convertMapStatuses.
+   * Create FetchShuffleBlocks message and rebuild internal blockIds by
+   * analyzing the pass in blockIds.
    */
-  private FetchShuffleBlocks createFetchShuffleBlocksMsg(
+  private FetchShuffleBlocks createFetchShuffleBlocksMsgAndBuildBlockIds(
       String appId, String execId, String[] blockIds) {
     String[] firstBlock = splitBlockId(blockIds[0]);
     int shuffleId = Integer.parseInt(firstBlock[1]);
     boolean batchFetchEnabled = firstBlock.length == 5;
 
-    HashMap<Long, ArrayList<Integer>> mapIdToReduceIds = new HashMap<>();
+    LinkedHashMap<Long, ArrayList<Integer>> mapIdToReduceIds = new LinkedHashMap<>();
+    LinkedHashMap<Long, ArrayList<String>> mapIdToBlockIds = new LinkedHashMap<>();

Review comment:
       Can we use a single map? we can create a `BlocksInfo` class here
   ```
   class BlocksInfo {
     ArrayList<Integer> reduceIds;
     ArrayList<String> blockIds;
   }
   
   LinkedHashMap<Long, BlocksInfo> mapIdToBlocksInfo = new LinkedHashMap<>();
   ```




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