[ https://issues.apache.org/jira/browse/DRILL-6063?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Sorabh Hamirwasia updated DRILL-6063: ------------------------------------- Labels: ready-to-commit (was: ) > Set correct ThreadContext ClassLoader before using Hadoop Configuration class > in DrillClient > -------------------------------------------------------------------------------------------- > > Key: DRILL-6063 > URL: https://issues.apache.org/jira/browse/DRILL-6063 > Project: Apache Drill > Issue Type: Improvement > Components: Client - Java > Affects Versions: 1.11.0 > Reporter: Sorabh Hamirwasia > Assignee: Sorabh Hamirwasia > Labels: ready-to-commit > Fix For: 1.13.0 > > > Drill Client uses Hadoop Configuration class in security mechanism factories. > Configuration class internally uses ThreadContext class loader to get the > default resources for configurations. When Drill JDBC driver is used with 3rd > party tool like Squirrel then it creates a class loader with all Drill Driver > related dependencies. This class loader is used to instantiate an object of > Driver class in a separate thread. But the thread context class loader has > dependencies related to Squirrel only. As a result of this when Hadoop > Configuration class tries to load the resources with default values it > doesn't find them in class path. > If we specify hadoop dependencies in Squirrel's classpath instead of Driver > dependencies class path then it will work since Thread Context class loader > will have Hadoop libraries loaded too and will find the resources. But this > is not good as it is tying up one Squirrel instance with one version of > Hadoop which might not be true in all the cases like here when same Squirrel > instance can be used to load multiple versions of Drill Driver having > different hadoop version dependencies. > To deal with this issue a simple fix is to set the Thread Context class > loader to be same as Drill Driver dependencies class loader before accessing > Hadoop Configuration class in Drill Client and later restore it back. > Some pointers in code: > * Place where JDBC driver is loaded as part of separate thread in Squirrel: > [OpenConnectionCommand.java|https://sourceforge.net/p/squirrel-sql/git/ci/master/tree/sql12/core/src/net/sourceforge/squirrel_sql/client/mainframe/action/OpenConnectionCommand.java#l167] > * Place where JDBC driver class is instantiated in Squirrel using Driver > dependencies class loader: > [SQLDriverManager.java|https://sourceforge.net/p/squirrel-sql/git/ci/master/tree/sql12/core/src/net/sourceforge/squirrel_sql/fw/sql/SQLDriverManager.java#l74] > * Place where Hadoop Configuration class looks into Thread Context Class > Loader: > [Configuration.java|https://github.com/apache/hadoop-common/blob/trunk/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/conf/Configuration.java#L615] -- This message was sent by Atlassian JIRA (v6.4.14#64029)