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https://issues.apache.org/jira/browse/SOLR-7282?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15344197#comment-15344197
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Noble Paul edited comment on SOLR-7282 at 6/22/16 12:24 PM:
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Looked at the patch. It's broken.
The way you cache things assume that schema is immutable. it is not.
{{IndexSchema}} can change all the time. So, the cache must be aware of the
znode version from where the schema is loaded.
There are two ways we can cache.
# Cache the schema file content and avoid reloading from ZK. This is low impact
and cheaper to implement but less beneficial. The cost of parsing the XML is
high. If we can pre-parse the XML and store them as Java objects and share this
java object it is faster.
# Cache the {{IndexSchema}} object. This would mean, we need to carefully look
at the lifecycle of components in {{IndexSchema}}. We will also have to keep in
mind that eventually we will have to support dynamic loading of components in
schema. I would say this is a risky path to take
was (Author: noble.paul):
Looked at the patch. It's broken.
The way you cache things assume that schema is immutable. it is not.
{{IndexSchema}} can change all the time. So, the cache must be aware of the
znode version from where the schema is loaded.
There are two ways we can cache.
# Cache the schema file content and avoid reloading from ZK. This is low impact
and cheaper to implement but less beneficial. The cost of parsing the XML is
high. If we can pre-parse the XML and store them as Java objects and share this
java object it is faster.
# Cache the {{IndexSchema}} object. This would mean, we need to carefully look
at the lifecycle of components in {{IndexSchema}}
> Cache config or index schema objects by configset and share them across cores
> -----------------------------------------------------------------------------
>
> Key: SOLR-7282
> URL: https://issues.apache.org/jira/browse/SOLR-7282
> Project: Solr
> Issue Type: Sub-task
> Components: SolrCloud
> Reporter: Shalin Shekhar Mangar
> Assignee: Shalin Shekhar Mangar
> Fix For: 5.2, 6.0
>
> Attachments: SOLR-7282.patch
>
>
> Sharing schema and config objects has been known to improve startup
> performance when a large number of cores are on the same box (See
> http://wiki.apache.org/solr/LotsOfCores).Damien also saw improvements to
> cluster startup speed upon caching the index schema in SOLR-7191.
> Now that SolrCloud configuration is based on config sets in ZK, we should
> explore how we can minimize config/schema parsing for each core in a way that
> is compatible with the recent/planned changes in the config and schema APIs.
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