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From "Alexey Serba (JIRA)" <>
Subject [jira] [Created] (SOLR-3587) Reloading a core is no longer updates analysis process
Date Mon, 02 Jul 2012 08:33:42 GMT
Alexey Serba created SOLR-3587:

             Summary: Reloading a core is no longer updates analysis process
                 Key: SOLR-3587
             Project: Solr
          Issue Type: Bug
    Affects Versions: 4.0
            Reporter: Alexey Serba

It's a usual practice in Solr to overwrite synonyms/stopwords files and issue a core reload
command to force Solr reload these files. We've noticed that this trick is no longer working
on trunk. 

I started debugging this problem in Eclipse and I can see that Solr actually re-reads updated
synonym file on core reload, but indexing process still uses old reference to Synonym filter
/ SynonymMap instance. 

When I start Solr initially I can see that my Solr server has 2 instances of SynonymMap (the
object that holds actual synonyms data). This is expected as I have 2 SynonymFilters defined
in my schema (one field with 2 synonym filters - index + query time)

After a core reload I see that Solr has 4 instances of this class. So I thought that there
could be some leak and issued many (N) core reload commands and expected to see 2*N instances.
It didn't happen. I can only see 20 instances of this class. 

This is pretty interesting number as well because, according to thread dump/list, Solr/Jetty
has 10 working threads in thread pool (by default for example configs). So I suspect that
we cache something in thread local storage and it hits us. 

I looked into the code and found that Lucene caches token streams in ThreadLocal, but I don't
know the code enough to state that this is the problem.

So I took a different approach and found the commit that introduced this bug. I wrote a simple
test (shell script) and used _git bisect_ tool to chase this bug.

ffd9c717448eca895d19be8ee9718bc399ac34a7 is the first bad commit
commit ffd9c717448eca895d19be8ee9718bc399ac34a7
Author: Mark Robert Miller <>
Date:   Thu Jun 30 13:59:59 2011 +0000

      SOLR-2193, SOLR-2565: The default Solr update handler has been improved so
      that it uses fewer locks, keeps the IndexWriter open rather than closing it
      on each commit (ie commits no longer wait for background merges to complete),
      works with SolrCore to provide faster 'soft' commits, and has an improved API
      that requires less instanceof special casing.
      You may now specify a 'soft' commit when committing. This will
      use Lucene's NRT feature to avoid guaranteeing documents are on stable storage in exchange
      for faster reopen times. There is also a new 'soft' autocommit tracker that can be
     SolrCores now properly share IndexWriters across SolrCore reloads.
    git-svn-id: 13f79535-47bb-0310-9956-ffa450edef68

It looks like sharing IndexWriters across SolrCore reloads could be the root cause, right?

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