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https://issues.apache.org/jira/browse/LUCENE-1720?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12833827#action_12833827
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Shai Erera commented on LUCENE-1720:
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Ok, it looks like ConcurrentHashMap cannot be used by ATM because of its
TimeoutThread. When the thread checks the map and iterates on its elements, we
need to lock the map completely because otherwise we can hit a case where the
thread pulled an entry for inspection, and then the thread which is monitored
calls stop(), but the timeout thread won't know that any might wrongly mark
that thread as a timeout activity thread ...
Since checkForTimeout does not need to obtain any lock, and the synchronization
happens on start/stop/isProjected and TimeoutThread, I'm not sure how important
is it to use CHM.
Another thing, CHM allows you to specify the concurrency level, which is
essentially the number of threads you know are going to 'change' the map (put
or remove). If you don't know that, and default to clevel=1, it means only one
thread is expected to change the map, which in ATM's case would yield to <0
benefit, since all the threads (which their number we don't know up front)
change the map ... of course we can guess, or try to, but ...
Anyway, I'm putting that aside for now, and moving no to adding more tests to
TestTimeLimitingReader.
bq. getWrappedReader
Mark, the exception in the tests is thrown from
SegmentReader.getOnlySegmentReader. I think if we add this method to
FilterIndexReader only and in getOnlySegmentReader we add this code:
{code}
if (reader instanceof FilterIndexReader) {
return getOnlySegmentReader(((FilterIndexReader) reader).getWrappedReader());
}
{code}
It should work? This can be done in this issue I think as it doesn't break
back-compat and exposes a reasonable method where it should be. What do you
think?
> TimeLimitedIndexReader and associated utility class
> ---------------------------------------------------
>
> Key: LUCENE-1720
> URL: https://issues.apache.org/jira/browse/LUCENE-1720
> Project: Lucene - Java
> Issue Type: New Feature
> Components: Index
> Reporter: Mark Harwood
> Assignee: Mark Harwood
> Priority: Minor
> Attachments: ActivityTimedOutException.java,
> ActivityTimeMonitor.java, ActivityTimeMonitor.java, ActivityTimeMonitor.java,
> Lucene-1720.patch, Lucene-1720.patch, LUCENE-1720.patch,
> TestTimeLimitedIndexReader.java, TestTimeLimitedIndexReader.java,
> TimeLimitedIndexReader.java, TimeLimitedIndexReader.java
>
>
> An alternative to TimeLimitedCollector that has the following advantages:
> 1) Any reader activity can be time-limited rather than just single searches
> e.g. the document retrieve phase.
> 2) Times out faster (i.e. runaway queries such as fuzzies detected quickly
> before last "collect" stage of query processing)
> Uses new utility timeout class that is independent of IndexReader.
> Initial contribution includes a performance test class but not had time as
> yet to work up a formal Junit test.
> TimeLimitedIndexReader is coded as JDK1.5 but can easily be undone.
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