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From "Michael McCandless (JIRA)" <j...@apache.org>
Subject [jira] [Created] (LUCENE-4462) Publishing flushed segments is single threaded and too costly
Date Fri, 05 Oct 2012 18:48:04 GMT
Michael McCandless created LUCENE-4462:
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             Summary: Publishing flushed segments is single threaded and too costly
                 Key: LUCENE-4462
                 URL: https://issues.apache.org/jira/browse/LUCENE-4462
             Project: Lucene - Core
          Issue Type: Improvement
            Reporter: Michael McCandless


Spinoff from http://lucene.markmail.org/thread/4li6bbomru35qn7w

The new TestBagOfPostings failed the build because it timed out after 2 hours ... but in digging
I found that it was a starvation issue: the 4 threads were flushing segments much faster than
the 1 thread could publish them.

I think this is because publishing segments (DocumentsWriter.publishFlushedSegment) is actually
rather costly (creates CFS file if necessary, writes .si, etc.).

I committed a workaround for now, to prevent starvation (see svn diff -c 1394704 https://svn.apache.org/repos/asf/lucene/dev/trunk),
but we really should address the root cause by moving these costly ops into flush() so that
publishing is a low cost operation.

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