Commands/perf

perf
Permission level required	4
Restrictions	Dedicated server only

Captures information and metrics about the game for ten seconds.

Note that this command can only executed in dedicated server, use F3 + L in client to run performance profiler.

Syntax

perf start

Starts a recording for 10 seconds performance profiling such as tick durations, used heap sizes and other more detailed stats.

perf stop

Ends the recording early before the 10-second limit.

Result

Command	Trigger	Java Edition
/perf start	a perf profiling session has already been started	Failed
/perf stop	there's no perf profiling session running.
any	Otherwise	Successful

Outputs

Command	Edition	Situation	Success Count	/execute store success ...	/execute store result ...
any	Java Edition	On fail	N/A	0	0
		On success	N/A	1	0

File structure

When perf profiling session is stopped, a ZIP file is created in .minecraft/debug/profiling with the following structure:

• yyyy-MM-dd_HH.mm.ss-<world name>-<game version>.zip
  • system.txt
  • server
    • deviations
      • ticktime
        • <current tick>@yyyy-MM-dd_HH.mm.ss.SSS.txt
    • levels
      • <namespace>
        • <dimension name>
          • block_entities.csv: Contains a list of block entities in the world in the format x,y,z,type.
          • chunks.csv: Contains a list of chunk information in the format x,z,level,in_memory,status,full_status,accessible_ready,ticking_ready,entity_ticking_ready,ticket,spawning,entity_count,block_entity_count.
          • entities.csv: Contains a list of entities in the world in the format x,y,z,uuid,type,alive,custom_name.
          • entity_chunks.csv: Contains a list of loaded chunks in the dimension in the format x,y,z,visibility,load_status,entity_count.
          • example_crash.txt: An example crash file.
          • stats.txt: Contains some stats.
    • metrics
      • cpu.csv
      • event_loops.csv
      • jvm.csv
      • mailboxes.csv
      • ticking.csv
    • classpath.txt: Contains the file paths of the external jars Minecraft uses.
    • gamerules.txt: A plain text file containing a list of game rules and their values (<gamerule>=<value>).
    • modules.txt: Contains the external modules jars Minecraft uses.
    • profiling.txt: The profiler results.
    • server.properties.txt: Current server.properties.
    • stats.txt: Contains some stats.
    • threads.txt: All running threads.

History

Java Edition
1.17		Pre-release 1			Added /perf.

Commands 

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