今天在測試spark-sql運行在yarn上的過程中，無意間從日志中發現了一個問題：
spark-sql --master yarn
14/12/29 15:23:17 INFO Client: Requesting a new application from cluster with 1 NodeManagers 14/12/29 15:23:17 INFO Client: Verifying our application has not requested more than the maximum memory capability of the cluster (8192 MB per container) 14/12/29 15:23:17 INFO Client: Will allocate AM container, with 896 MB memory including 384 MB overhead 14/12/29 15:23:17 INFO Client: Setting up container launch context for our AM 14/12/29 15:23:17 INFO Client: Preparing resources for our AM container 14/12/29 15:23:17 INFO Client: Uploading resource file:/home/spark/software/source/compile/deploy_spark/assembly/target/scala-2.10/spark-assembly-1.3.0-SNAPSHOT-hadoop2.3.0-cdh5.0.0.jar -> hdfs://hadoop000:8020/user/spark/.sparkStaging/application_1416381870014_0093/spark-assembly-1.3.0-SNAPSHOT-hadoop2.3.0-cdh5.0.0.jar 14/12/29 15:23:18 INFO Client: Setting up the launch environment for our AM container
再開啟一個spark-sql命令行，從日志中再次發現：
14/12/29 15:24:03 INFO Client: Requesting a new application from cluster with 1 NodeManagers 14/12/29 15:24:03 INFO Client: Verifying our application has not requested more than the maximum memory capability of the cluster (8192 MB per container) 14/12/29 15:24:03 INFO Client: Will allocate AM container, with 896 MB memory including 384 MB overhead 14/12/29 15:24:03 INFO Client: Setting up container launch context for our AM 14/12/29 15:24:03 INFO Client: Preparing resources for our AM container 14/12/29 15:24:03 INFO Client: Uploading resource file:/home/spark/software/source/compile/deploy_spark/assembly/target/scala-2.10/spark-assembly-1.3.0-SNAPSHOT-hadoop2.3.0-cdh5.0.0.jar -> hdfs://hadoop000:8020/user/spark/.sparkStaging/application_1416381870014_0094/spark-assembly-1.3.0-SNAPSHOT-hadoop2.3.0-cdh5.0.0.jar 14/12/29 15:24:05 INFO Client: Setting up the launch environment for our AM container
然后查看HDFS上的文件：
hadoop fs -ls hdfs://hadoop000:8020/user/spark/.sparkStaging/
drwx------ - spark supergroup 0 2014-12-29 15:23 hdfs://hadoop000:8020/user/spark/.sparkStaging/application_1416381870014_0093 drwx------ - spark supergroup 0 2014-12-29 15:24 hdfs://hadoop000:8020/user/spark/.sparkStaging/application_1416381870014_0094
每個Application都會上傳一個spark-assembly-x.x.x-SNAPSHOT-hadoopx.x.x-cdhx.x.x.jar的jar包，影響HDFS的性能以及占用HDFS的空間。
在Spark文檔(http://spark.apache.org/docs/latest/running-on-yarn.html)中發現spark.yarn.jar屬性，將spark-assembly-xxxxx.jar存放在hdfs://hadoop000:8020/spark_lib/下
在spark-defaults.conf添加屬性配置：
spark.yarn.jar hdfs://hadoop000:8020/spark_lib/spark-assembly-1.3.0-SNAPSHOT-hadoop2.3.0-cdh5.0.0.jar
再次啟動spark-sql --master yarn觀察日志：
14/12/29 15:39:02 INFO Client: Requesting a new application from cluster with 1 NodeManagers
14/12/29 15:39:02 INFO Client: Verifying our application has not requested more than the maximum memory capability of the cluster (8192 MB per container)
14/12/29 15:39:02 INFO Client: Will allocate AM container, with 896 MB memory including 384 MB overhead
14/12/29 15:39:02 INFO Client: Setting up container launch context for our AM
14/12/29 15:39:02 INFO Client: Preparing resources for our AM container
14/12/29 15:39:02 INFO Client: Source and destination file systems are the same. Not copying hdfs://hadoop000:8020/spark_lib/spark-assembly-1.3.0-SNAPSHOT-hadoop2.3.0-cdh5.0.0.jar
14/12/29 15:39:02 INFO Client: Setting up the launch environment for our AM container
觀察HDFS上文件
hadoop fs -ls hdfs://hadoop000:8020/user/spark/.sparkStaging/application_1416381870014_0097
該Application對應的目錄下沒有spark-assembly-xxxxx.jar了，從而節省assembly包上傳的過程以及HDFS空間占用。
我在測試過程中遇到了類似如下的錯誤：
Application application_xxxxxxxxx_yyyy failed 2 times due to AM Container for application_xxxxxxxxx_yyyy
exited with exitCode: -1000 due to: java.io.FileNotFoundException: File /tmp/hadoop-spark/nm-local-dir/filecache does not exist
在/tmp/hadoop-spark/nm-local-dir路徑下創建filecache文件夾即可解決報錯問題。