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From "Shai Erera (JIRA)" <>
Subject [jira] Commented: (LUCENE-1720) TimeLimitedIndexReader and associated utility class
Date Mon, 29 Jun 2009 12:09:47 GMT


Shai Erera commented on LUCENE-1720:

In stop(), shouldn't the 'else' part be reached only if the firstAnticipatedThreadToFail ==
Thread.currentThread()? Currently, if no thread has timed out, and I'm not the firstAnticipatedThreadToFail,
the code will still look for a new candidate, and probably find the same firstAnticipatedThreadToFail.

Also, even though that's somewhat mentioned in the class, we don't support multiple timing
out threads, and I'm not sure if that's good. Currently, if two threads time out, and the
calling thread to checkTimeOutIsThisThread() is not firstAnticipatedThreadToFail, it will
continue processing. That may not be good, if the other thread is busy-waiting somewhere,
and may not call checkTimeOutIsThisThread for a long time.

What if we change firstAnticipatedThreadToFail to a HashSet and call contains()? It's slower
than '==', but safer, which is also an important aspect of this utility. TimeoutThread can
add all the timeoud threads to this HashSet, when it detects a timeout has occurred (by iterating
on all the 'registered' threads and their expected time out time, and compare to the current
time). What do you think?

> TimeLimitedIndexReader and associated utility class
> ---------------------------------------------------
>                 Key: LUCENE-1720
>                 URL:
>             Project: Lucene - Java
>          Issue Type: New Feature
>          Components: Index
>            Reporter: Mark Harwood
>            Assignee: Mark Harwood
>            Priority: Minor
>         Attachments:,,,
> 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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