012huang opened a new pull request #27060: [SPARK-30246][CORE][SHUFFLE]fix spark external shuffle memory leak URL: https://github.com/apache/spark/pull/27060 ### What changes were proposed in this pull request? An app finished abnormal sometimes may cause shuffe service memory leak. In one of our production cases, the app failed for Stage cancelled as SparkContext has already shut down. the strange is there are still requests for fetch shuffle data and cause error in server side as below: ``` 2019-12-08 22:23:33,375 ERROR server.TransportRequestHandler (TransportRequestHandler.java:processFetchRequest(132)) - Error opening block StreamChunkId{streamId=1902064894814, chunkIndex=0} for request from /10.221.115.175:38582 java.lang.RuntimeException: Executor is not registered (appId=application_1574499669561_954327, execId=4514) ``` the client sie also show corresponding log like this: ``` org.apache.spark.shuffle.FetchFailedException: Failure while fetching StreamChunkId{streamId=1902064894814, chunkIndex=0}: java.lang.RuntimeException: Executor is not registered (appId=application_1574499669561_954327, execId=4514) ``` in some cases, the request for `OpenBlocks` is still on the fly. In the code `ExternalShuffleBlockHandler#handleMessage`, it will register a `StreamState` to `OneForOneStreamManager#streams`, then reply an success response to client unconditionally , the client receive the response and then fire `ChunkFetchRequest` to fetch chunk, but at this time, the app has got event `APPLICATION_STOP` and executed `ExternalShuffleService#applicationRemoved` method to clean the app's `ExecutorShuffleInfo`, this made `Executor is not registered` error happended. even though when the client channel is closing, the `TransportRequestHandler#channelInactive` was called to clean the StreamState with relate channel, but when cleanning the `StreamState buffter`, it also lookup `ManagedBuffer` with` appId` and `execId` info which have been cleaned in executors object. we can also find the log: `StreamManager connectionTerminated() callback failed` in NM's log file. so, when an `OpenBlocks` request come, we should lookup `ExternalShuffleBlockResolver#executors` , if the realted app is exited, we should not registering a `StreamState` and just close the client (or reply an special message to client and in client side to handle it). and when an app get `APPLICATION_STOP` to call `applicationRemoved`, we should clean the the related `streamState` before `ExecutorShuffleInfo` has been cleaned, this is what the PR changes and prevents the shuffle service memory leak. ### Why are the changes needed? The external shuffle service memory leak has a great impact on cluster with dynanic on and may cause NM crash. ### Does this PR introduce any user-facing change? No ### How was this patch tested? with existing ut
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