https://wiki.sasgaming.net/index.php?action=history&feed=atom&title=Minecraft%3ACommands%2FjfrMinecraft:Commands/jfr - Revision history2026-04-09T14:33:25ZRevision history for this page on the wikiMediaWiki 1.43.8https://wiki.sasgaming.net/index.php?title=Minecraft:Commands/jfr&diff=49713&oldid=previmported>Outrowed: separate WP and JEP linking2025-03-30T03:47:01Z<p>separate WP and JEP linking</p>
<p><b>New page</b></p><div>{{Exclusive|java}}<br />
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{{Infobox command<br />
|name=jfr<br />
|oplevel=4<br />
}}<br />
<br />
Starts and stops profiling with {{w|Java Flight Recorder}} ([https://openjdk.java.net/jeps/328 JEP]) as well as a few custom events.<br />
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==Usage==<br />
When profiling, it records several information about CPU, memory, and threads usage of the client while it was running, and saves them on a <code>.jfr</code> file under the {{cd|[[Minecraft:.minecraft]]/debug}} folder.<br />
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The file can be opened using an external tool or software, such as [https://visualvm.github.io/ VisualVM] or [https://github.com/openjdk/jmc JMC]. It contains JVM and operating system events, with several ''Minecraft''-related custom events below:<br />
<!-- Documentation with names taken from VisualVM program --><br />
* '''Network''' group, which contains:<br />
**'''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.<br />
**'''Network Summary''': summary information of received and sent packets count and their bytes size.<br />
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* '''Storage''' group, which contains:<br />
** '''Region File Read''' and '''Region File Write''': [[Minecraft:region file]] events, containing information about region and chunk positions, dimension, and type of compression algorithm.<br />
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* '''Ticking''' group, which only contains a single custom event:<br />
**'''Server Tick Time''': sampling event of the average server tick duration at one second intervals.<br />
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*'''World Generation''' group, which contains:<br />
**'''Chunk Generation''': time taken to generate individual [[Minecraft:chunk]] stages.<br />
**'''Create/Load World''': initial [[Minecraft:world]] loading duration when loading a world.<br />
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The <code>.jfr</code> file is accompanied by a summary [[Minecraft:JSON]] report is written both to the log file and in the debug folder.<br />
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== Syntax ==<br />
:<code>jfr start</code><br />
:: Start JFR profiling.<br />
:<code>jfr stop</code><br />
:: Stop JFR profiling.<br />
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== Result ==<br />
{{Result table|onlyje=1}}<br />
{{Result table|The command is incomplete, or any argument is not specified correctly.|unparseable}}<br />
{{Result table|cmd=/jfr start|A jfr profiler has already been started.|fail}}<br />
{{Result table|cmd=/jfr stop|There's no jfr profiler running.}}<br />
{{Result table|cmd=|succeed}}<br />
{{Result table}}<br />
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== Output ==<br />
{{Output table}}<br />
{{Output table|edition=je|On fail|N/A|0|0}}<br />
{{Output table|On success|N/A|1|1}}<br />
{{Output table}}<br />
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== History ==<br />
{{HistoryTable<br />
|{{HistoryLine|java}}<br />
|{{HistoryLine||1.18|dev=21w37a|Added {{cmd|jfr|link=none}}.}}<br />
}}<br />
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== Navigation ==<br />
{{Navbox commands}}<br />
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[[Minecraft:de:Befehl/jfr]]<br />
[[Minecraft:es:Comandos/jfr]]<br />
[[Minecraft:ja:コマンド/jfr]]<br />
[[Minecraft:lzh:令/jfr]]<br />
[[Minecraft:pt:Comandos/jfr]]<br />
[[Minecraft:zh:命令/jfr]]</div>imported>Outrowed