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https://issues.apache.org/jira/browse/PHOENIX-4860?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16587764#comment-16587764
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James Taylor commented on PHOENIX-4860:
---------------------------------------
Thanks for letting us know about this, Jack. There shouldn't be a static Map in
CursorUtil. That's a flawed design. Instead, that map should live as a member
variable on PhoenixConnection. The CursorUtil.openCursor() call already takes a
Connection argument, and the closeCursor() should take one as well, so the
change could be minimal and best course of action IMHO.
> CursorUtil Needs to Use a ConcurrentHashMap rather than HashMap
> ---------------------------------------------------------------
>
> Key: PHOENIX-4860
> URL: https://issues.apache.org/jira/browse/PHOENIX-4860
> Project: Phoenix
> Issue Type: Bug
> Affects Versions: 4.14.0, 4.13.1, 5.0.0
> Reporter: Jack Steenkamp
> Priority: Major
> Attachments: CursorUtil.patch
>
>
> in very rare cases, when dealing with Apache Phoenix Cursors, the following
> NullPointerException is encountered:
> java.lang.NullPointerException: null
> at org.apache.phoenix.util.CursorUtil.updateCursor(CursorUtil.java:179)
> at
> org.apache.phoenix.iterate.CursorResultIterator.next(CursorResultIterator.java:46)
> at org.apache.phoenix.jdbc.PhoenixResultSet.next(PhoenixResultSet.java:779)
> (This is for 4.13.1 - but seems that
> org.apache.phoenix.util.CursorUtil has not changed, at the time of writing,
> since first being introduced as part of PHOENIX-3572).
> Upon closer inspection it would seem that on line 124 of CursorUtil, a
> HashMap is used to keep state which is then exposed via a number of
> static methods, which, one has to assume, can be accessed by many
> different threads. Using a plain old HashMap in cases like these can cause
> issues.
> The mapCursorIDQuery member should be a ConcurrentHashMap instead? That
> should tighten up the class and prevent any potential inconsistencies.
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