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How to use Spark commands

Spark is a performance analysis tool for Minecraft servers. Spark helps check TPS, profile CPU usage, dump the heap, and produce health reports.

Basic usage

Commands can be run from:

  • the console, without a leading /
  • in-game, with a leading /

Commonly used commands

Command Function
/spark tps View the server's TPS
/spark profiler start Start the profiler
/spark profiler stop Stop the profiler and create a result
/spark profiler open Open the latest profiler result
/spark health --upload Create a health report and upload it
/spark gc View the garbage collection history
/spark heapdump Write a heap dump to disk

How to find the cause of lag

  1. Run /spark profiler start.
  2. Let the server run while the lag happens.
  3. Run /spark profiler stop.
  4. Open the result with /spark profiler open.

Important notes

  • According to the official spark documentation, /spark gc shows garbage collection history; it is not a magic button that "frees RAM" permanently.
  • The documented official command for a health report is /spark health, not /spark healthreport.

Extra analysis examples

  • /spark profiler start --timeout 60 for a 60-second auto-stop profiler
  • /spark health --upload to generate a shareable report

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Cheers, Team NexusCloud