My RAM keeps rising and never drops (memory leak) — is that normal? How do I fix it? — Minecraft

Q: How do I find which mod is leaking?

Run /spark heapsummary to see what's holding memory, then update or remove the suspect and test.

RAM that climbs steadily and never drops can look alarming, but it's only a real problem if it ends in a crash. Java naturally holds memory high — a true memory leak is when usage keeps rising until the server runs out and crashes, usually because of a specific mod or plugin.

Is it actually a leak?

First, tell the difference:

Just sitting high — normal JVM behavior, nothing to fix.
Climbing steadily until it crashes with OutOfMemory — that's a leak worth chasing.

How to fix a leak

Confirm it truly crashes — look for OutOfMemory in the Console, rather than just high-but-stable usage.
Run a spark heap report with /spark heapsummary to see what's holding memory.
Update or remove the suspect mod or plugin.
Set a sensible RAM buffer in the Startup tab so a spike doesn't hard-crash the server.
Schedule a periodic restart (via the Schedules tab) to clear accumulated memory as a stopgap.

Tip: High-but-stable RAM is fine — only a steady climb that ends in an OutOfMemory crash points to an actual leak.

Frequently asked questions

My RAM is high but the server never crashes — is that a leak? No. That's normal Java behavior. A leak specifically ends in an OutOfMemory crash.

How do I find which mod is leaking? Run /spark heapsummary to see what's holding memory, then update or remove the suspect and test.