Minecraft:Commands/jfr

Starts and stops profiling with Template:W (JEP) as well as a few custom events.

Usage

When profiling, it records several information about CPU, memory, and threads usage of the client while it was running, and saves them on a .jfr file under the Template:Cd folder.

The file can be opened using an external tool or software, such as VisualVM or JMC. It contains JVM and operating system events, with several Minecraft-related custom events below:

• Network group, which contains:
  • Network Packet Received and Network Packet Sent: network packet events, containing information about their protocol ID, packet ID, packet direction (server or client bound), remote address, and bytes size. See Minecraft:Java Edition protocol for list of protocol and packet IDs.
  • Network Summary: summary information of received and sent packets count and their bytes size.

• Storage group, which contains:
  • Region File Read and Region File Write: Minecraft:region file events, containing information about region and chunk positions, dimension, and type of compression algorithm.

• Ticking group, which only contains a single custom event:
  • Server Tick Time: sampling event of the average server tick duration at one second intervals.

• World Generation group, which contains:
  • Chunk Generation: time taken to generate individual Minecraft:chunk stages.
  • Create/Load World: initial Minecraft:world loading duration when loading a world.

The .jfr file is accompanied by a summary Minecraft:JSON report is written both to the log file and in the debug folder.

Syntax

jfr start

Start JFR profiling.

jfr stop

Stop JFR profiling.