Polyhedron

Prism / MultiMC log parsing & analysis library

Parsing

A log has the following structure. The header contains information such as mods, Java args, and other information known before starting the game and some information from the launcher pre-initialization phase. The entries after contain various timestamped events from the initialization phase and everything from when the game is running. The footer contains the exit code and if applicable other information such as JRE crash information.

block
  columns 3
  h["Header"]:5
  block:group1:2
    columns 4
    time1["Time"] thread1["Thread"] level1["Level"] context1["Context"]
  end
  content1["Contents"]:3
  block:group2:2
    columns 4
    time2["Time"] thread2["Thread"] level2["Level"] context2["Context"]
  end
  content2["Contents"]:3
  block:group3:2
    columns 4
    time3["Time"] thread3["Thread"] level3["Level"] context3["Context"]
  end
  content3["Contents"]:3
  f["Footer"]:5

Loading

Polyhedron is written to allow streaming data from logs, whether that be from a HTTP request stream or from an actively running game. This is why most checks work with LogEntry's instead of reading the log as as string.

Header parsing (src/header)

The header is initially indexed to find standard positions (src/header/index.rs). This is done to reduce parsing complexity and improve performance. This produces the IndexedLogHeader which is used in all the checks. It can be used to extract used mods, MC info, Java info, libraries etc.

pie title Top 5 most common Minecraft versions
	"1.20.1" : 1117
	"1.21.1" : 490
	"1.21.10" : 314
	"1.21.11" : 274
	"1.21.8" : 254

Loading

Most commonly used Minecraft versions based on headers of 4.6k logs (2026-03)

Log entry parsing (src/entries)

Log entries are parsed into a LogEntry struct with separate fields for each "column". This allows for filtering based on log level, thread, or class context. It also makes it easier to more reliably parse the contents of log entries such as stacktraces. It supports a wide variety of log formats and localization options.

Unparsed

[18:33:36] [main/WARN]: Reference map 'xaerominimap.refmap.json' for xaerominimap.mixins.json could not be read. If this is a development environment you can ignore this message
[18:33:36] [main/WARN]: Reference map 'yet_another_config_lib_v3.refmap.json' for yacl-fabric.mixins.json could not be read. If this is a development environment you can ignore this message
[18:33:36] [main/WARN]: Error loading class: net/raphimc/immediatelyfast/feature/core/BatchableBufferSource (java.lang.ClassNotFoundException: net/raphimc/immediatelyfast/feature/core/BatchableBufferSource)
[18:33:36] [main/WARN]: Error loading class: net/irisshaders/batchedentityrendering/impl/FullyBufferedMultiBufferSource (java.lang.ClassNotFoundException: net/irisshaders/batchedentityrendering/impl/FullyBufferedMultiBufferSource)
[18:33:37] [main/WARN]: Error loading class: dev/isxander/controlify/virtualmouse/VirtualMouseHandler (java.lang.ClassNotFoundException: dev/isxander/controlify/virtualmouse/VirtualMouseHandler)
[18:33:37] [main/WARN]: @Mixin target dev.isxander.controlify.virtualmouse.VirtualMouseHandler was not found mixins.ipnext.json:MixinVirtualMouseHandler from mod inventoryprofilesnext
[18:33:37] [main/WARN]: Force-disabling mixin 'features.render.world.sky.LevelRendererMixin' as rule 'mixin.features.render.world.sky' (added by mods [iris]) disables it and children
[18:33:38] [main/INFO]: Starting Essential Loader (stage2) version 1.6.6 (64b13bbd248a9bb10a3dc68389eacdcc) [stable]
[18:33:39] [main/INFO]: Starting Essential v1.3.10.4 (#9adecc609e) [stable]
[18:33:39] [main/INFO]: Java: OpenJDK 64-Bit Server VM (v21.0.7) by Microsoft (Microsoft)
[18:33:39] [main/INFO]: Java Info: mixed mode

Parsed

Hour	Minute	Second	Thread	Level	Contents
18	33	36	main	WARN	Reference map 'xaerominimap.refmap.json' for xaerominimap.mixins.json could not be read. If this is a development environment you can ignore this message
18	33	36	main	WARN	Reference map 'yet_another_config_lib_v3.refmap.json' for yacl-fabric.mixins.json could not be read. If this is a development environment you can ignore this message
18	33	36	main	WARN	Error loading class: net/raphimc/immediatelyfast/feature/core/BatchableBufferSource (java.lang.ClassNotFoundException: net/raphimc/immediatelyfast/feature/core/BatchableBufferSource)
18	33	36	main	WARN	Error loading class: net/irisshaders/iris/layer/InnerWrappedRenderType (java.lang.ClassNotFoundException: net/irisshaders/iris/layer/InnerWrappedRenderType)
18	33	37	main	WARN	Error loading class: dev/isxander/controlify/virtualmouse/VirtualMouseHandler (java.lang.ClassNotFoundException: dev/isxander/controlify/virtualmouse/VirtualMouseHandler)
18	33	37	main	WARN	@Mixin target dev.isxander.controlify.virtualmouse.VirtualMouseHandler was not found mixins.ipnext.json:MixinVirtualMouseHandler from mod inventoryprofilesnext
18	33	37	main	WARN	Force-disabling mixin 'features.render.world.sky.LevelRendererMixin' as rule 'mixin.features.render.world.sky' (added by mods [iris]) disables it and children
18	33	38	main	INFO	Starting Essential Loader (stage2) version 1.6.6 (64b13bbd248a9bb10a3dc68389eacdcc) [stable]
18	33	39	main	INFO	Starting Essential v1.3.10.4 (#9adecc609e) [stable]
18	33	39	main	INFO	Java: OpenJDK 64-Bit Server VM (v21.0.7) by Microsoft (Microsoft)
18	33	39	main	INFO	Java Info: mixed mode

Issue detection (src/issues)

src/issues/issue.rs contains an enum that represent all detectable issues. src/issues/checks contains various checks that produce these issues based on the header, log entries, stacktraces, and / or exit code.