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https://issues.apache.org/jira/browse/SOLR-14923?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17213094#comment-17213094
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Thomas Wöckinger commented on SOLR-14923:
-----------------------------------------
Nearly the same results when moving (line 688 to 694)
RefCounted<SolrIndexSearcher> holder = uhandler.core.openNewSearcher(true,
true);
out of the synchronized block, so a performance boost of factor 26 at least!
I don't know how is responsible for this part of code.
The final implementation of the method would be:
{code:java}
//
public void openRealtimeSearcher() {
try {
RefCounted<SolrIndexSearcher> holder =
uhandler.core.openNewSearcher(true, true);
holder.decref();
} catch (Exception e) {
SolrException.log(log, "Error opening realtime searcher", e);
return;
}
synchronized (this) {
// We must cause a new IndexReader to be opened before anything looks at
these caches again
// so that a cache miss will read fresh data. if (map != null)
map.clear();
if (prevMap != null) prevMap.clear();
if (prevMap2 != null) prevMap2.clear();
}
}
{code}
Side effects are open for discussion, may [~erickerickson] , [~dsmiley] ,
[~noble.paul] or [~ab] have some input on this change
> Indexing performance is unacceptable when child documents are involved
> ----------------------------------------------------------------------
>
> Key: SOLR-14923
> URL: https://issues.apache.org/jira/browse/SOLR-14923
> Project: Solr
> Issue Type: Bug
> Security Level: Public(Default Security Level. Issues are Public)
> Components: update, UpdateRequestProcessors
> Affects Versions: master (9.0), 8.3, 8.4, 8.5, 8.6
> Reporter: Thomas Wöckinger
> Priority: Critical
> Labels: performance
>
> Parallel indexing does not make sense at moment when child documents are used.
> The org.apache.solr.update.processor.DistributedUpdateProcessor checks at the
> end of the method doVersionAdd if Ulog caches should be refreshed.
> This check will return true if any child document is included in the
> AddUpdateCommand.
> If so ulog.openRealtimeSearcher(); is called, this call is very expensive,
> and executed in a synchronized block of the UpdateLog instance, therefore all
> other operations on the UpdateLog are blocked too.
> Because every important UpdateLog method (add, delete, ...) is done using a
> synchronized block almost each operation is blocked.
> This reduces multi threaded index update to a single thread behavior.
> The described behavior is not depending on any option of the UpdateRequest,
> so it does not make any difference if 'waitFlush', 'waitSearcher' or
> 'softCommit' is true or false.
> The described behavior makes the usage of ChildDocuments useless, because the
> performance is unacceptable.
>
>
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