Details
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Bug
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Status: Closed
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Major
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Resolution: Won't Fix
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5.3
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None
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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.