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From Jack Steenkamp <steenkamp.j...@gmail.com>
Subject CursorUtil -> mapCursorIDQuery
Date Tue, 21 Aug 2018 13:48:45 GMT
Hi All,

In my application I make heavy use of Apache Phoenix's Cursors
(https://phoenix.apache.org/cursors.html) - and for the majority of
cases it works great and makes my life a lot easier (thanks for
implementing them). However, in very rare cases (fiendishly rare
cases), I get NullpointerExceptions such as the following:

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 much since it was
first created).

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
static methods, which, one has to assume, can be accessed by many
different threads. Using a plain old HashMap in cases like these have
(at least in my experience) been to blame for rare issues such as
these.

Would you perhaps consider changing the implementation of
mapCursorIDQuery to a ConcurrentHashMap instead? That should hopefully
tighten up the class and prevent any potential inconsistencies.

Regards,

Jack Steenkamp

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