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From "Daniel Blum (JIRA)" <j...@apache.org>
Subject [jira] [Created] (ACCUMULO-4435) WholeColumnFamilyIterator doesn't work after re-init
Date Wed, 31 Aug 2016 17:08:21 GMT
Daniel Blum created ACCUMULO-4435:
-------------------------------------

             Summary: WholeColumnFamilyIterator doesn't work after re-init
                 Key: ACCUMULO-4435
                 URL: https://issues.apache.org/jira/browse/ACCUMULO-4435
             Project: Accumulo
          Issue Type: Bug
          Components: core
    Affects Versions: 1.6.5
            Reporter: Daniel Blum
            Priority: Minor


When using WholeColumnFamilyIterator this exception is thrown:

{noformat}
java.lang.IllegalStateException: never been seeked
        at org.apache.accumulo.core.iterators.WrappingIterator.hasTop(WrappingIterator.java:80)
        at org.apache.accumulo.core.iterators.user.WholeColumnFamilyIterator.hasTop(WholeColumnFamilyIterator.java:213)
        at org.apache.accumulo.core.iterators.system.SourceSwitchingIterator.readNext(SourceSwitchingIterator.java:132)
        at org.apache.accumulo.core.iterators.system.SourceSwitchingIterator.seek(SourceSwitchingIterator.java:167)
        at org.apache.accumulo.tserver.Tablet.lookup(Tablet.java:1523)
        at org.apache.accumulo.tserver.Tablet.lookup(Tablet.java:1630)
        at org.apache.accumulo.tserver.TabletServer$ThriftClientHandler$LookupTask.run(TabletServer.java:1155)
        at org.apache.accumulo.trace.instrument.TraceRunnable.run(TraceRunnable.java:47)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
        at org.apache.accumulo.trace.instrument.TraceRunnable.run(TraceRunnable.java:47)
        at org.apache.accumulo.core.util.LoggingRunnable.run(LoggingRunnable.java:34)
        at java.lang.Thread.run(Thread.java:745)
{noformat}

I THINK this is caused by re-initialization of the iterator stack. When this happens WCFI.seek()
may end up returning without calling seek() on its source (because it gets a range with effectively
nothing in it). This would be fine except that WCFI.hasTop() calls hasTop() on its source;
since the source has not been seeked yet, the exception is thrown.

WholeRowIterator does not run into this problem in spite of using the same seek logic because
its hasTop (actually RowEncodingIterator.hasTop) does not check the source's hasTop. (The
way RowEncodingIterator and WCFI handle all of this does not really conform to the interface
definition - they should really keep track themselves of whether they have been seeked and
throw the appropriate exceptions.)

I actually encountered this in 1.6.2, but I can't select that as a version here. I believe
the problem also exists in 1.6.5 (and 1.7.2) based on inspecting the source, but cannot test
with those versions right now to confirm.



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