vanzin commented on a change in pull request #26869: [SPARK-30235][CORE] Switching off host local disk reading of shuffle blocks in case of useOldFetchProtocol URL: https://github.com/apache/spark/pull/26869#discussion_r358432368
########## File path: docs/sql-migration-guide.md ########## @@ -97,7 +97,7 @@ license: | - Since Spark 3.0, when Avro files are written with user provided non-nullable schema, even the catalyst schema is nullable, Spark is still able to write the files. However, Spark will throw runtime NPE if any of the records contains null. - - Since Spark 3.0, we use a new protocol for fetching shuffle blocks, for external shuffle service users, we need to upgrade the server correspondingly. Otherwise, we'll get the error message `UnsupportedOperationException: Unexpected message: FetchShuffleBlocks`. If it is hard to upgrade the shuffle service right now, you can still use the old protocol by setting `spark.shuffle.useOldFetchProtocol` to `true`. + - Since Spark 3.0, we use a new protocol for fetching shuffle blocks, for external shuffle service users, we need to upgrade the server correspondingly. Otherwise, we'll get the error message `IllegalArgumentException: Unexpected message type: <number>`. If it is hard to upgrade the shuffle service right now, you can still use the old protocol by setting `spark.shuffle.useOldFetchProtocol` to `true`. Review comment: Since you're changing this, this item is pretty hard to read. Better: ``` Since Spark 3.0, a new protocol for fetching shuffle blocks is used. It's recommended that external shuffle services be upgraded when running Spark 3.0 apps. Old external shuffle services can still be used by setting the configuration `spark.shuffle.useOldFetchProtocol` to `true`. Otherwise, Spark may run into errors with messages like `Illegal ...`. ``` (On a side note, the "Since Spark blah.blah" thing on every item is pretty redundant; having proper subsections would be better, like in the core guide. But not something to change here. But now that I mention this, this item really should be in the core guide, not in the SQL guide.) ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: [email protected] With regards, Apache Git Services --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
