🧠💥 Solr JVM Tuning RAM & Memory Management

Solr’s RAM appetite is legendary. Don’t worry, you’re not alone. Let’s help you keep your heap happy, your queries snappy, and your boss off your back.

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🤔 Why Does Solr Use So Much Memory?

• Search results: Returns tons of docs? RAM feast.
• Caches: Four flavors, all with big appetites.
• Big fields, bad configs, massive requests: Boom—there goes your heap.
• Solr: “Give me RAM, and I shall give you… maybe some results.”

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🛠️ Best Practices, in Style

1. Save Bandwidth, Save RAM

Fewer bytes → less RAM.
See our bandwidth tips.

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2. Limit the rows Parameter!

Don’t return all the docs unless you want Solr to host a BBQ in your memory.

&rows=100

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3. Paginate Responsibly

Huge start values = huge RAM usage.
Try not to cross start=50000 unless you really like chaos.

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4. docValues or Bust

Faceting, sorting, grouping, highlighting:

<field name="my_field" docValues="true" type="string" indexed="true" stored="true"/>

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5. Cache, but Not Like a Hoarder

Tighten up your caches in solrconfig.xml.

<filterCache size="1" initialSize="1" autowarmCount="0"/>

Monitor cache hit ratios; <10% = wasted RAM.

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6. JVM Heap: Not a Dumpster, Not a Bathtub

• Heap size:
  For most, 4g or 8g is enough.
  -Xms4g -Xmx4g
• Garbage Collector:
  Use G1GC (modern, less “stop the world”). -XX:+UseG1GC
• GC Tuning:
  For Solr 8+: -XX:+UseStringDeduplication -XX:MaxGCPauseMillis=200
• Monitor:
  If your GC logs show frequent full GCs, it’s time to optimize.
  Enable GC logging for real insight: -Xlog:gc*:file=/var/solr/gc.log:time,uptime,level,tags:filecount=10,filesize=10M

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7. Watch the Heap & GC

• In Solr Admin UI, watch for heap >85% or long GC pauses.
• If your server pauses for coffee breaks, that’s bad news.

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8. Index Analytics & Log Watching

• Use the Opensolr Analytics panel to see who/what is eating RAM.
• Tail your logs and spot traffic spikes—don’t wait for support to call you.

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9. Drupal + Solr = PATCH NOW

Keep Search API Solr current or face the wrath of bugs.

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🎯 TL;DR Pro Tips

• Limit rows and start.
• Use docValues for anything you facet, sort, or group.
• Cache like you’re paying rent by the megabyte.
• Tune JVM heap and GC for your workload, not someone else’s.
• Watch logs, heap, and GC stats.
• Patch integrations, always.

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🧑‍🔬 JVM Tuning Quick Reference

JVM Option	What It Does	Default/Example
-Xms / -Xmx	Min/Max heap size	-Xms4g -Xmx4g
-XX:+UseG1GC	Use the G1 Garbage Collector	Always for Java 8+
-XX:MaxGCPauseMillis=200	Target max GC pause time (ms)	-XX:MaxGCPauseMillis=200
-XX:+UseStringDeduplication	Remove duplicate strings in heap	Java 8u20+
-Xlog:gc*	GC logging	See above
-XX:+HeapDumpOnOutOfMemoryError	Write heap dump on OOM	Always!
-XX:HeapDumpPath=/tmp/solr-heapdump.hprof	Path for OOM heap dump	Set to a safe disk

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🤪 Meme Zone: Solr Memory Edition

“How many docs can I return? Solr: Yes.”

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🤝 When to Call for Backup

• Heap usage feels like the national debt
• Solr restarts become your afternoon coffee break
• JVM heap dumps are bigger than your backup drive

👉 Contact Opensolr Support — bring logs, configs, and memes. We love a challenge.