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https://issues.apache.org/jira/browse/DRILL-5874?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16206370#comment-16206370
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ASF GitHub Bot commented on DRILL-5874:
---------------------------------------
Github user paul-rogers commented on a diff in the pull request:
https://github.com/apache/drill/pull/993#discussion_r144930316
--- Diff:
exec/java-exec/src/main/java/org/apache/drill/exec/server/rest/WebUserConnection.java
---
@@ -124,6 +124,13 @@ public void sendData(RpcOutcomeListener<Ack> listener,
QueryWritableBatch result
}
}
+ /**
+ * Returns a DefaultChannelPromise which doesn't have reference to any
actual channel but has an EventExecutor
+ * associated with it. In this case we use EventExecutor out of
BitServer EventLoopGroup. Since there is no actual
+ * connection established using this class, hence the close event will
never be fired by underlying layer and close
+ * future is set only when the WebSessionResources are closed.
--- End diff --
Can we take this comment up a level? This is a description of the
mechanics, which is fine. But, what is the intent?
Are we using a web session as a pseudo-connection (as described in earlier
comments)? Is this an adapter to make the session look like a connection?
> NPE in AnonWebUserConnection.cleanupSession()
> ---------------------------------------------
>
> Key: DRILL-5874
> URL: https://issues.apache.org/jira/browse/DRILL-5874
> Project: Apache Drill
> Issue Type: Bug
> Affects Versions: 1.12.0
> Reporter: Paul Rogers
> Assignee: Sorabh Hamirwasia
> Fix For: 1.12.0
>
>
> When debugging another issue, I tried to use the Web UI to run the example
> query:
> {code}
> SELECT * FROM cp.`employee.json` LIMIT 20
> {code}
> The query failed with this error:
> {noformat}
> Query Failed: An Error Occurred
> java.lang.NullPointerException
> {noformat}
> No stack trace was provided in the log, even at DEBUG level.
> Debugging, the problem appears to be deep inside
> {{AnonWebUserConnection.cleanupSession()}}:
> {code}
> package io.netty.channel;
> public class DefaultChannelPromise ...
> protected EventExecutor executor() {
> EventExecutor e = super.executor();
> if (e == null) {
> return channel().eventLoop();
> } else {
> return e;
> }
> }
> {code}
> In the above, {{channel()}} is null. the {{channel}} field is also null.
> This may indicate that some part of the Web UI was not set up correctly. This
> is a recent change, as this code worked several days ago.
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