🧠💥 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.

🤔 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.”

🛠️ Best Practices, in Style

1. Save Bandwidth, Save RAM

Fewer bytes → less RAM.
See our bandwidth tips.

2. Limit the `rows` Parameter!

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

&rows=100

3. Paginate Responsibly

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

4. docValues or Bust

Faceting, sorting, grouping, highlighting:

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

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.

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
```

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.

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.

9. Drupal + Solr = PATCH NOW

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

🎯 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.

🧑‍🔬 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

🤪 Meme Zone: Solr Memory Edition

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

🤝 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.