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https://issues.apache.org/jira/browse/DRILL-3822?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14903742#comment-14903742
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Daniel Barclay (Drill) commented on DRILL-3822:
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> The question is why this fix [1] is causing issues in this situation.
I think it's because we're not constraining PathScanner more narrowly so
that it uses its own class loader (the class loader that loaded it (the
one created by SQuirreL for driver isolation)) rather than the thread's
context class loader (which SQuirreL apparently didn't change from the
default--but should it have?).
> PathScanner fails to find jdbc-all's drill-module.conf in SQuirreL
> ------------------------------------------------------------------
>
> Key: DRILL-3822
> URL: https://issues.apache.org/jira/browse/DRILL-3822
> Project: Apache Drill
> Issue Type: Bug
> Components: Client - JDBC
> Affects Versions: 1.2.0
> Reporter: Krystal
> Assignee: Daniel Barclay (Drill)
> Attachments: squirrel.log
>
>
> git.commit.id.abbrev=3c89b30
> I used the latest drill-jdbc-all-1.2.0-SNAPSHOT.jar against the SQuirreL SQL
> application. I got the following error when trying to connect to the drill
> data source:
> {noformat}
> ERROR net.sourceforge.squirrel_sql.client.gui.db.ConnectToAliasCallBack -
> Unexpected Error occurred attempting to open an SQL connection.
> java.util.concurrent.ExecutionException: java.lang.RuntimeException:
> oadd.com.typesafe.config.ConfigException$Missing: No configuration setting
> found for key 'drill.exec'
> Full error message is in the attached file.
> {noformat}
> We turned on logging and found that the jdbc-all Jar file's
> {{drill-module.conf}} file was not being found (explaining why the
> configuration key {{drill.exec}} wasn't found).
> After further investigation, it seems that {{PathScanner}} directly uses the
> system class loader, bypassing the context class loader.
> (After drill-jdbc-all-1.2.0-SNAPSHOT.jar was changed from being listed in
> SQuirreL's "additional class paths" (presumably being loaded by a special
> class loader) to being copied into SQuirreL's Jar file directory (and
> therefore loaded by the system class loader), SQuirreL worked. (Apparently,
> {{PathScanner}} was then able to find {{drill-module.conf}} in the JDBC-all
> Jar file and load it, so the later reference to {{drill.exec}} no longer
> failed.)
> Also, SQuirreL works correctly with drill-1.1's JDBC-all Jar file, and there
> were some recent changes to {{PathScanner}} related to class loaders.)
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