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From Apache Wiki <wikidi...@apache.org>
Subject [Solr Wiki] Update of "FAQ" by ShawnHeisey
Date Fri, 27 Jul 2018 17:55:19 GMT
Dear Wiki user,

You have subscribed to a wiki page or wiki category on "Solr Wiki" for change notification.

The "FAQ" page has been changed by ShawnHeisey:
https://wiki.apache.org/solr/FAQ?action=diff&rev1=105&rev2=106

Comment:
Improve section about maxWarmingSearchers

  The most common cause is from using a version of Solr+Lucene that is older then the version
used to create that index.
  
  == What does "exceeded limit of maxWarmingSearchers=X" mean? ==
- Whenever a commit happens in Solr, a new "searcher" (with new caches) is opened, "warmed"
up according to your SolrConfigXml settings, and then put in place.  The previous searcher
is not closed until the "warming" search is ready.  If multiple commits happen in rapid succession
-- before the warming searcher from first commit has enough time to warm up, then there can
be multiple searchers all competeing for resources at the same time, even htough one of them
will be thrown away as soon as the next one is ready.
+ Whenever a commit happens in Solr, a new "searcher" (with new caches) is opened, "warmed"
up according to your SolrConfigXml settings, and then put in place.  The previous searcher
is not closed until the "warming" search is ready.  If multiple commits happen in rapid succession,
then a searcher may still be warming up when another commit comes in.  This will cause multiple
searchers to be started and warming at the same time, all competing for resources.  Only one
searcher is ever actively handling queries at a time -- all old searchers are thrown away
when the latest one finishes warming.
  
- maxWarmingSearchers is a setting in SolrConfigXml that helps you put a safety valve on the
number of overlapping warming searchers that can exist at one time.  If you see this error
it means Solr prevented a commit from resulting an a new searcher being opened because there
were already X warming searchers open.
+ maxWarmingSearchers is a setting in SolrConfigXml that helps you put a safety valve on the
number of overlapping warming searchers that can exist at one time.  If you see this error
it means Solr prevented a new searcher from being opened because there were already X searchers
warming up.
  
- If you encounter this error a lot, you can (in theory) increase the number in your maxWarmingSearchers,
but that is risky to do unless you are confident you have the system resources (RAM, CPU,
etc...) to do it safely.  A more correct way to deal with the situation is to reduce how frequently
you send commits.
+ The best way to prevent this log message is to reduce the frequency of commit operations.
 Enough time should pass between commits for each commit to completely finish.
  
+ If you encounter this error a lot, you can increase the number for maxWarmingSearchers,
but this is usually the wrong thing to do.  It requires significant system resources (RAM,
CPU, etc...) to do it safely, and it can drastically affect Solr's performance.
+ 
- If you only encounter this error infrequently because of fluke situations, you'll probably
be ok just ignoring it.
+ If you only encounter this error infrequently because of an unusually high load on the system,
you'll probably be OK just ignoring it.
  
  == Why doesn't my index directory get smaller (immediately) when i delete documents? force
a merge? optimize? ==
  

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