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From "Andrey Kudryavtsev (JIRA)" <j...@apache.org>
Subject [jira] [Comment Edited] (SOLR-9330) Race condition between core reload and statistics request
Date Tue, 20 Sep 2016 20:16:20 GMT

    [ https://issues.apache.org/jira/browse/SOLR-9330?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15507657#comment-15507657
] 

Andrey Kudryavtsev edited comment on SOLR-9330 at 9/20/16 8:16 PM:
-------------------------------------------------------------------

If we are talking about root cause of the race - it looks like things are a little bit more
easily than I thought. There is just another  thread executor in CoreAdminHandler. If there
will be API to avoid it, reload operation will become more synchronous (patch is attached).

I thought that it will require to do something like too_sync.patch, but not this time probably.



was (Author: werder):
If we are talking about root cause of the race - it looks like things are a little bit more
easily than I thought. There is just another  thread executor in CoreAdminHandler. If there
will be API to avoid it, reload operation will become more synchronous (patch is attached).

It thought that it will require to do something like too_sync.patch, but not this time probably.


> Race condition between core reload and statistics request
> ---------------------------------------------------------
>
>                 Key: SOLR-9330
>                 URL: https://issues.apache.org/jira/browse/SOLR-9330
>             Project: Solr
>          Issue Type: Bug
>      Security Level: Public(Default Security Level. Issues are Public) 
>    Affects Versions: 5.5
>            Reporter: Andrey Kudryavtsev
>         Attachments: SOLR-9330.patch, SOLR-9390.patch, SOLR-9390.patch, SOLR-9390.patch,
too_sync.patch
>
>
> Things happened that we execute this two requests consecutively in Solr 5.5:
> * Core reload: /admin/cores?action=RELOAD&core=_coreName_
> * Check core statistics: /_coreName_/admin/mbeans?stats=true
> And sometimes second request ends with this error:
> {code}
> ERROR org.apache.solr.servlet.HttpSolrCall - null:org.apache.lucene.store.AlreadyClosedException:
this IndexReader is closed
> 	at org.apache.lucene.index.IndexReader.ensureOpen(IndexReader.java:274)
> 	at org.apache.lucene.index.StandardDirectoryReader.getVersion(StandardDirectoryReader.java:331)
> 	at org.apache.lucene.index.FilterDirectoryReader.getVersion(FilterDirectoryReader.java:119)
> 	at org.apache.lucene.index.FilterDirectoryReader.getVersion(FilterDirectoryReader.java:119)
> 	at org.apache.solr.search.SolrIndexSearcher.getStatistics(SolrIndexSearcher.java:2404)
> 	at org.apache.solr.handler.admin.SolrInfoMBeanHandler.addMBean(SolrInfoMBeanHandler.java:164)
> 	at org.apache.solr.handler.admin.SolrInfoMBeanHandler.getMBeanInfo(SolrInfoMBeanHandler.java:134)
> 	at org.apache.solr.handler.admin.SolrInfoMBeanHandler.handleRequestBody(SolrInfoMBeanHandler.java:65)
> 	at org.apache.solr.handler.RequestHandlerBase.handleRequest(RequestHandlerBase.java:155)
> 	at org.apache.solr.core.SolrCore.execute(SolrCore.java:2082)
> 	at org.apache.solr.servlet.HttpSolrCall.execute(HttpSolrCall.java:670)
> 	at org.apache.solr.servlet.HttpSolrCall.call(HttpSolrCall.java:458)
> 	at org.apache.solr.servlet.SolrDispatchFilter.doFilter(SolrDispatchFilter.java:225)
> 	at org.apache.solr.servlet.SolrDispatchFilter.doFilter(SolrDispatchFilter.java:183)
> {code}
> If my understanding of SolrCore internals is correct, it happens because of async nature
of reload request:
> * New searcher is "registered" in separate thread
> * Old searcher is closed in same separate thread and only after new one is registered
> * When old searcher is closing, it removes itself from map with MBeans 
> * If statistic requests happens before old searcher is completely removed from everywhere
- exception can happen. 
> What do you think if we will introduce new parameter for reload request which makes it
fully synchronized? Basically it will force it to call {code}  SolrCore#getSearcher(boolean
forceNew, boolean returnSearcher, final Future[] waitSearcher, boolean updateHandlerReopens)
{code} with waitSearcher!= null



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