xuanyuanking commented on a change in pull request #28965:
URL: https://github.com/apache/spark/pull/28965#discussion_r448830595
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File path: core/src/main/scala/org/apache/spark/util/JsonProtocol.scala
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@@ -1078,8 +1078,12 @@ private[spark] object JsonProtocol {
val blockManagerAddress = blockManagerIdFromJson(json \ "Block Manager
Address")
val shuffleId = (json \ "Shuffle ID").extract[Int]
val mapId = (json \ "Map ID").extract[Long]
- val mapIndex = (json \ "Map Index") match {
- case JNothing => 0
+ val mapIndex = json \ "Map Index" match {
+ case JNothing =>
+ // Note, we use the invalid value -2 here to fill the map index
for backward
+ // compatibility. Otherwise, the fetch failed event will be
dropped when the history
+ // server loads the event log written by the Spark version before
3.0.
+ -2
Review comment:
Thanks Gengliang for confirming!
```
Any special reasons using -2 instead of -1?
```
mapIndex = -1 has been used in `MetadataFetchFailedException`.
Yep, I think `Int.MinValue` is a better choice.
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