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Apache Solr Reference Guide Covering Apache Solr 6.0

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socketTimeout 0 (use OS default) The amount of time in ms that a socket is allowed to<br />

wait.<br />

connTimeout 0 (use OS default) The amount of time in ms that is accepted for binding /<br />

connecting a socket<br />

maxConnectionsPerHost 20 The maximum number of concurrent connections that is<br />

made to each individual shard in a distributed search.<br />

maxConnections 10000 The total maximum number of concurrent connections<br />

in distributed searches.<br />

corePoolSize 0 The retained lowest limit on the number of threads used<br />

in coordinating distributed search.<br />

maximumPoolSize Integer.MAX_VALUE The maximum number of threads used for coordinating<br />

distributed search.<br />

maxThreadIdleTime 5 seconds The amount of time to wait for before threads are<br />

scaled back in response to a reduction in load.<br />

sizeOfQueue -1 If specified, the thread pool will use a backing queue<br />

instead of a direct handoff buffer. High throughput<br />

systems will want to configure this to be a direct hand<br />

off (with -1). Systems that desire better latency will want<br />

to configure a reasonable size of queue to handle<br />

variations in requests.<br />

fairnessPolicy false Chooses the JVM specifics dealing with fair policy<br />

queuing, if enabled distributed searches will be handled<br />

in a First in First out fashion at a cost to throughput. If<br />

disabled throughput will be favored over latency.<br />

Configuring statsCache (Distributed IDF)<br />

Document and term statistics are needed in order to calculate relevancy. <strong>Solr</strong> provides four implementations out<br />

of the box when it comes to document stats calculation:<br />

LocalStatsCache: This only uses local term and document statistics to compute relevance. In cases<br />

with uniform term distribution across shards, this works reasonably well.<br />

This option is the default if no is configured.<br />

ExactStatsCache: This implementation uses global values (across the collection) for document<br />

frequency.<br />

ExactSharedStatsCache: This is exactly like the exact stats cache in it's functionality but the global<br />

stats are reused for subsequent requests with the same terms.<br />

LRUStatsCache: This implementation uses an LRU cache to hold global stats, which are shared<br />

between requests.<br />

The implementation can be selected by setting in solrconfig.xml. For example, the<br />

following line makes <strong>Solr</strong> use the ExactStatsCache implementation:<br />

<br />

Avoiding Distributed Deadlock<br />

<strong>Apache</strong> <strong>Solr</strong> <strong>Reference</strong> <strong>Guide</strong> <strong>6.0</strong><br />

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