Commands/perf

This feature is exclusive to Java Edition.

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.	Failed
any	Otherwise	Successful

Outputs[]

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