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Marcelo Vanzin resolved SPARK-19501. ------------------------------------ Resolution: Fixed Assignee: Jong Wook Kim Fix Version/s: 2.2.0 2.1.1 2.0.3 > Slow checking if there are many spark.yarn.jars, which are already on HDFS > -------------------------------------------------------------------------- > > Key: SPARK-19501 > URL: https://issues.apache.org/jira/browse/SPARK-19501 > Project: Spark > Issue Type: Improvement > Components: YARN > Affects Versions: 2.0.0, 2.0.1, 2.1.0 > Reporter: Jong Wook Kim > Assignee: Jong Wook Kim > Priority: Minor > Fix For: 2.0.3, 2.1.1, 2.2.0 > > > Hi, this is my first Spark issue submission and please excuse any > inconsistencies. > I am experiencing a slower application startup time when I specify many files > as {{spark.yarn.jars}}, by setting it as all JARs in an HDFS folder, such as > {{hdfs://namenode/user/spark/lib/*.jar}}. > Since the JAR files are already on the same HDFS that YARN is running, the > application should be very fast to startup. However, the delay is significant > especially when {{spark-submit}} is running from a non-local network, because > {{spark-yarn}} accesses the individual JAR files via HDFS, adding hundreds of > RTT before the application is ready. The official spark distribution with > Hadoop 2.7 has more than 200 jars, and >100 even if we exclude Hadoop and its > dependencies. > There are currently two HDFS RPC calls for each file, once at > {{ClientDistributedCacheManager.addResource}} calling {{fs.getFileStatus}}, > and another at {{yarn.Client.copyFileToRemote}} calling {{fc.resolvePath}}. I > suppose that both are unnecessary, since we [already retrieved all > FileStatuses, and that those are not > symlinks|https://github.com/apache/spark/blob/v2.1.0/yarn/src/main/scala/org/apache/spark/deploy/yarn/Client.scala#L531]. > To fix this, I suppose that we can modify {{addResource}} to use its > {{statCache}} variable before making an HDFS RPC and populate {{statCache}} > appropriately before calling {{addResource}}. Also, an optional boolean > parameter of {{copyFileToRemote}} can be added to skip the symlink check. -- This message was sent by Atlassian JIRA (v6.3.15#6346) --------------------------------------------------------------------- To unsubscribe, e-mail: issues-unsubscr...@spark.apache.org For additional commands, e-mail: issues-h...@spark.apache.org