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  1. Lucene - Core
  2. LUCENE-6811

AnalyzingInfixSuggester cannot be used in more than one thread

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    Details

    • Type: Bug
    • Status: Closed
    • Priority: Major
    • Resolution: Won't Fix
    • Affects Version/s: 5.3
    • Fix Version/s: None
    • Component/s: modules/other
    • Labels:
    • Lucene Fields:
      New

      Description

      Currently AnalyzingInfixSuggester always opens an index writer, even if the suggester will be used entirely in read-only mode. I was trying to serve suggestions out of the same index in a multithreaded setup, but I could only create one suggester per index per process because of this design.

      I've created a GitHub project to demonstrate the bug: https://github.com/lukhnos/lucene-analyzing-infix-suggester-bug

      To run the demo:

      ./gradlew build
      java -jar build/libs/lucene-analyzing-infix-suggester-bug.jar
      

      The exception reads:

      Exception in thread "Thread-1" java.lang.RuntimeException: org.apache.lucene.store.LockObtainFailedException: Lock held by this virtual machine: <INDEX DIR>/write.lock
          at org.lukhnos.lucenestudy.AnalyzingInfixSuggesterBug$1SuggestReader.run(AnalyzingInfixSuggesterBug.java:65)
          at java.lang.Thread.run(Thread.java:745)
      Caused by: org.apache.lucene.store.LockObtainFailedException: Lock held by this virtual machine: <INDEX DIR>/write.lock
          at org.apache.lucene.store.NativeFSLockFactory.obtainFSLock(NativeFSLockFactory.java:127)
          at org.apache.lucene.store.FSLockFactory.obtainLock(FSLockFactory.java:41)
          at org.apache.lucene.store.BaseDirectory.obtainLock(BaseDirectory.java:45)
          at org.apache.lucene.index.IndexWriter.<init>(IndexWriter.java:775)
          at org.apache.lucene.search.suggest.analyzing.AnalyzingInfixSuggester.<init>(AnalyzingInfixSuggester.java:251)
          at org.apache.lucene.search.suggest.analyzing.AnalyzingInfixSuggester.<init>(AnalyzingInfixSuggester.java:163)
          at org.lukhnos.lucenestudy.AnalyzingInfixSuggesterBug$1SuggestReader.run(AnalyzingInfixSuggesterBug.java:51)
          ... 1 more
      

      To work around this problem, I'm currently using my own modified "read only" AnalyzingInfixSuggester, in which I commented out the index writer creation code in the constructor. Then, in the lookup method, I also commented out the part where we get an EarlyTerminatingSortingCollector out of the index writer, so that only a TopFieldCollector is used.

      I was wondering if a read-only mode can be added to AnalyzingInfixSuggester, or at least the contract of getIndexWriterConfig can be changed – since one will have to subclass to use a different index writer config anyway – such that if one returns null in getIndexWriterConfig, the suggester will operate in read-only mode, and so no index writer is created. Of course an error will have to be thrown if any build or update methods are called in such mode.

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            • Assignee:
              Unassigned
              Reporter:
              lukhnos Lukhnos Liu
            • Votes:
              1 Vote for this issue
              Watchers:
              3 Start watching this issue

              Dates

              • Created:
                Updated:
                Resolved: