On each and every open of the material editor, shader compiler threads are triggered, even if just opening a material without doing any changes.
Also toggling LivePreview in the material editor kicks off compiler threads (I usually keep this disabled, but within the editor, each click triggers shader compiles, endlessly).
For performance reasons and energy savings, I disable any realtime stuff, so even in content browser, I disabled the Real Time Thumbnails.
These compiles are triggered by missed cache shader maps as found in logs, here some examples:
LogAssetEditorSubsystem: Opening Asset editor for Material /Game/WaterHFCM/M_HerbWater_6.M_HerbWater_6
LogMaterial: Display: Missing cached shader map for material M_HerbWater_6, compiling.
LogMaterial: Display: Missing cached shader map for material M_HerbWater_6, compiling.
LogMaterial: Display: Missing cached shader map for material M_HerbWater_6, compiling.
LogShaderCompilers: Display: Worker (1/5): shaders left to compile 45
...
LogMaterial: Display: Missing cached shader map for material FMatExpressionPreview MaterialExpressionTextureSampleParameter2D_2, compiling.
LogMaterial: Display: Missing cached shader map for material FMatExpressionPreview MaterialExpressionConstant3Vector_0, compiling.
...
Why do these not get cached? I assume, it should be cached in the Derived Data Cache. I moved this away from my small SSD on C Drive to another disk, using the Editor Preferences:
These are the cache related log entries at UE4Editor start:
LogDerivedDataCache: Loaded boot cache 0.45s 75MB C:/Users/herbert/AppData/Local/UnrealEngine/4.25/DerivedDataCache/Boot.ddc.
LogDerivedDataCache: Display: Loaded Boot cache: C:/Users/herbert/AppData/Local/UnrealEngine/4.25/DerivedDataCache/Boot.ddc
LogDerivedDataCache: FDerivedDataBackendGraph: Pak pak cache file ../../../../../../_Projects/Unreal/Water/DerivedDataCache/DDC.ddp not found, will not use a pak cache.
LogDerivedDataCache: Unable to find inner node Pak for hierarchical cache Hierarchy.
LogDerivedDataCache: FDerivedDataBackendGraph: CompressedPak pak cache file ../../../../../../_Projects/Unreal/Water/DerivedDataCache/Compressed.ddp not found, will not use a pak cache.
LogDerivedDataCache: Unable to find inner node CompressedPak for hierarchical cache Hierarchy.
LogDerivedDataCache: Display: Pak cache opened for reading ../../../Engine/DerivedDataCache/Compressed.ddp.
LogDerivedDataCache: FDerivedDataBackendGraph: EnterprisePak pak cache file ../../../Enterprise/DerivedDataCache/Compressed.ddp not found, will not use a pak cache.
LogDerivedDataCache: Unable to find inner node EnterprisePak for hierarchical cache Hierarchy.
LogDerivedDataCache: Using Local data cache path E:/UE4_ddc: Writable
LogDerivedDataCache: Shared data cache path not found in *engine.ini, will not use an Shared cache.
LogDerivedDataCache: Unable to find inner node Shared for hierarchical cache Hierarchy.
As to my DDC path, this seems to be correct and it also finds, that I do not want to use a Shared DDC.
Checking places, where DerivedDataCache entries exist:
On system SSD, only the boot.ddc file seems to be present:
C:\Users\herbert\AppData\Local\UnrealEngine\4.25\DerivedDataCache\boot.ddc (ca. 70MB) - seems to be written on each editor close + empty directory "VT"
C:\Users\herbert\AppData\Local\UnrealEngine\Common\DerivedDataCache - empty
On my HDD, I find these:
E:\_Projects\Unreal\Water\DerivedDataCache - just an empty directory "VT"
E:\Programs\Epic Games\UE_4.25\Engine\DerivedDataCache - Compressed.ddp (ca. 800MB, not touched since 23.07.)
E:\UE4_ddc - lots of numbered subdirectories - current timestamps for content, so this is, where my stuff actually seems to be written as desired
Any tips what might cause the shaders not to be cached? I found similar threads but no solution.
Thank you