From a6e6fbf2ca23e51d43f175907ce6f29c946e1acf Mon Sep 17 00:00:00 2001 From: Dongjoon Hyun Date: Sat, 11 Apr 2020 08:27:30 -0700 Subject: [PATCH] [SPARK-31422][CORE] Fix NPE when BlockManagerSource is used after BlockManagerMaster stops ### What changes were proposed in this pull request? This PR (SPARK-31422) aims to return empty result in order to avoid `NullPointerException` at `getStorageStatus` and `getMemoryStatus` which happens after `BlockManagerMaster` stops. The empty result is consistent with the current status of `SparkContext` because `BlockManager` and `BlockManagerMaster` is already stopped. ### Why are the changes needed? In `SparkEnv.stop`, the following stop sequence is used and `metricsSystem.stop` invokes `sink.stop`. ``` blockManager.master.stop() metricsSystem.stop() --> sinks.foreach(_.stop) ``` However, some sink can invoke `BlockManagerSource` and ends up with `NullPointerException` because `BlockManagerMaster` is already stopped and `driverEndpoint` became `null`. ``` java.lang.NullPointerException at org.apache.spark.storage.BlockManagerMaster.getStorageStatus(BlockManagerMaster.scala:170) at org.apache.spark.storage.BlockManagerSource$$anonfun$10.apply(BlockManagerSource.scala:63) at org.apache.spark.storage.BlockManagerSource$$anonfun$10.apply(BlockManagerSource.scala:63) at org.apache.spark.storage.BlockManagerSource$$anon$1.getValue(BlockManagerSource.scala:31) at org.apache.spark.storage.BlockManagerSource$$anon$1.getValue(BlockManagerSource.scala:30) ``` Since `SparkContext` registers and forgets `BlockManagerSource` without deregistering, we had better avoid `NullPointerException` inside `BlockManagerMaster` preventively. ```scala _env.metricsSystem.registerSource(new BlockManagerSource(_env.blockManager)) ``` ### Does this PR introduce any user-facing change? Yes. This will remove NPE for the users who uses `BlockManagerSource`. ### How was this patch tested? Pass the Jenkins with the newly added test cases. Closes #28187 from dongjoon-hyun/SPARK-31422. Authored-by: Dongjoon Hyun Signed-off-by: Dongjoon Hyun --- .../spark/storage/BlockManagerMaster.scala | 2 ++ .../storage/BlockManagerMasterSuite.scala | 35 +++++++++++++++++++ 2 files changed, 37 insertions(+) create mode 100644 core/src/test/scala/org/apache/spark/storage/BlockManagerMasterSuite.scala diff --git a/core/src/main/scala/org/apache/spark/storage/BlockManagerMaster.scala b/core/src/main/scala/org/apache/spark/storage/BlockManagerMaster.scala index e335eb6ddb761..e440c1ab7bcd9 100644 --- a/core/src/main/scala/org/apache/spark/storage/BlockManagerMaster.scala +++ b/core/src/main/scala/org/apache/spark/storage/BlockManagerMaster.scala @@ -167,10 +167,12 @@ class BlockManagerMaster( * amount of remaining memory. */ def getMemoryStatus: Map[BlockManagerId, (Long, Long)] = { + if (driverEndpoint == null) return Map.empty driverEndpoint.askSync[Map[BlockManagerId, (Long, Long)]](GetMemoryStatus) } def getStorageStatus: Array[StorageStatus] = { + if (driverEndpoint == null) return Array.empty driverEndpoint.askSync[Array[StorageStatus]](GetStorageStatus) } diff --git a/core/src/test/scala/org/apache/spark/storage/BlockManagerMasterSuite.scala b/core/src/test/scala/org/apache/spark/storage/BlockManagerMasterSuite.scala new file mode 100644 index 0000000000000..0d54726af7ee8 --- /dev/null +++ b/core/src/test/scala/org/apache/spark/storage/BlockManagerMasterSuite.scala @@ -0,0 +1,35 @@ +/* + * Licensed to the Apache Software Foundation (ASF) under one or more + * contributor license agreements. See the NOTICE file distributed with + * this work for additional information regarding copyright ownership. + * The ASF licenses this file to You under the Apache License, Version 2.0 + * (the "License"); you may not use this file except in compliance with + * the License. You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ + +package org.apache.spark.storage + +import org.junit.Assert.assertTrue + +import org.apache.spark.{SparkConf, SparkFunSuite} + +class BlockManagerMasterSuite extends SparkFunSuite { + + test("SPARK-31422: getMemoryStatus should not fail after BlockManagerMaster stops") { + val bmm = new BlockManagerMaster(null, null, new SparkConf, true) + assertTrue(bmm.getMemoryStatus.isEmpty) + } + + test("SPARK-31422: getStorageStatus should not fail after BlockManagerMaster stops") { + val bmm = new BlockManagerMaster(null, null, new SparkConf, true) + assertTrue(bmm.getStorageStatus.isEmpty) + } +}