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From ivakegg <...@git.apache.org>
Subject [GitHub] accumulo issue #260: ACCUMULO-4643 initial implementation
Date Thu, 01 Jun 2017 13:31:10 GMT
Github user ivakegg commented on the issue:

    https://github.com/apache/accumulo/pull/260
  
    @phrocker I apologize, but either I am missing something or I have not adequately explained
what is going on here.  First and foremost, no iterator will ever yield unless somebody explicitly
writes an iterator that does.  Yields are never forced.  This is completely cooperative yielding.
 If somebody writes an iterator that does yield, then the iterator should only yield if it
is taking too much time between keys being returned.  In other words, if the iterator decides
to yield often then it will suffer in overall performance.  There will only be an increase
in RPC calls if the iterator yields when there are keys in the buffer, but we have not reached
scan max memory.  Yes, long scans will continue to be long.  This mechanism is simply to allow
the system being developed to avoid starvation of short running scans if they cannot afford
to increase the number of threads.


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