IssueTracker

Please find the required data below: Android Studio version: Android Studio Ladybug Feature Drop | 2024.2.2 OS type and version: Microsoft Windows 10 Pro (10.0.19045 Build 19045)

I didn't have screenshots now. The issue I faced is that, when changing some code in the XML file, it take more time to reflect in the preview than usual. And sometimes, after opening the project, the preview takes more time to load and shows a loader with message 'Initializing'.

There is a frequent exception logged as a warning, in conjunction with "Recomputed N fields for..." logging (sometimes duplicated for the same fqn? see the 464 fields below):

2025-01-09 18:20:05,404 [28441383]   INFO - #o.j.a.a.InnerRClassBase - Recomputed 987 fields for ResourceRepositoryInnerRClass{fqn=com.sensei.engrow.R.string, repository=AppResourceRepository@709C7B72}
2025-01-09 18:20:19,922 [28455901]   INFO - #com.android.ddmlib - Device 'motorola-moto_g52-ZD22262ND3' jdwp process '17149' is now known as pkg='com.sensei.engrow.alpha.ro.debug' (proc='com.sensei.engrow.alpha.ro.debug')
2025-01-09 18:23:02,900 [28618879]   INFO - #o.j.a.a.InnerRClassBase - Recomputed 464 fields for ResourceRepositoryInnerRClass{fqn=com.sensei.engrow.R.layout, repository=AppResourceRepository@709C7B72}
2025-01-09 18:23:02,906 [28618885]   INFO - #o.j.a.a.InnerRClassBase - Recomputed 464 fields for ResourceRepositoryInnerRClass{fqn=com.sensei.engrow.R.layout, repository=AppResourceRepository@573BFD3D}
2025-01-09 18:23:02,908 [28618887]   INFO - #o.j.a.a.InnerRClassBase - Recomputed 169 fields for ResourceRepositoryInnerRClass{fqn=com.sensei.engrow.test.R.layout, repository=TestAppResourceRepository@13D0D7B5}
2025-01-09 18:23:03,284 [28619263]   INFO - #c.i.d.JVMResponsivenessMonitor - JVM responsiveness: {avg: 2520.7322222222224, 50%: 1900, 99%: 15303, 99.9%: 26911, max: 35327 }ns, x{3600 measurements}
2025-01-09 18:23:20,756 [28636735]   WARN - #o.j.k.i.b.p.ModuleInfoProvider - Could not find correct module information
org.jetbrains.kotlin.utils.KotlinExceptionWithAttachments: Analyzing element of type class com.intellij.psi.impl.source.PsiJavaFileImpl in non-physical file of type class com.intellij.psi.impl.source.PsiJavaFileImpl
	at org.jetbrains.kotlin.idea.base.projectStructure.ModuleInfoProvider.collectByElement(ModuleInfoProvider.kt:193)
	at org.jetbrains.kotlin.idea.base.projectStructure.ModuleInfoProvider.access$collectByElement(ModuleInfoProvider.kt:73)
	at org.jetbrains.kotlin.idea.base.projectStructure.ModuleInfoProvider$collect$1.invoke(ModuleInfoProvider.kt:108)
	at org.jetbrains.kotlin.idea.base.projectStructure.ModuleInfoProvider$collect$1.invoke(ModuleInfoProvider.kt:107)
	at org.jetbrains.kotlin.idea.base.util.SeqKt$seq$$inlined$Sequence$1.iterator(Sequences.kt:682)
	at org.jetbrains.kotlin.idea.base.projectStructure.ModuleInfoProviderKt$unwrap$1$iterator$1.<init>(ModuleInfoProvider.kt:488)
	at org.jetbrains.kotlin.idea.base.projectStructure.ModuleInfoProviderKt$unwrap$1.iterator(ModuleInfoProvider.kt:487)
	at kotlin.sequences.SequencesKt___SequencesKt.firstOrNull(_Sequences.kt:167)
	at org.jetbrains.kotlin.idea.base.projectStructure.ModuleInfoProviderUtils.firstOrNull(ModuleInfoProviderUtils.kt:43)

I suspect the non-physical PsiJavaFileImpl is an R class. I found https://youtrack.jetbrains.com/issue/KTIJ-12550/Exception-during-completion-of-unimported-R-classes-in-Android-Studio-3.3-and-3.4 in which the exception message included the fully-qualified class name, and it was one of our light R classes.

As for preview rendering, I tried opening four layout files from Signal-Android and the majority of time is spent in reflection:

Eugene, do you know which JBR has the fix for https://bugs.openjdk.org/browse/JDK-8318563?

It was only 21.0.3b509.4 version with a fix: from Ladybug.1 Canary 1 till Canary 8

We lost patch in subsequent JBR update. ouch.

PS. Here's the async-profiler flame graph of the same: Note the FieldStreamBase::next calls, as a result of upstream commit bfb812a8ff8 implementing https://bugs.openjdk.org/browse/JDK-8292818.

In the above flame graph, loadIdsFromResourceClass has 26,531 CPU samples (42.19%). Here's the same code running on JBR17, only 3,010 CPU samples (8.81%):

Over to Diego. We patched https://bugs.openjdk.org/browse/JDK-8318563 but the code paths in the async-profiler snapshot above are not covered, i.e. the calls through fieldDescriptor::reinitialize -> InstanceKlass::field -> FieldStreamBase::next result in quadratic complexity iterating over the field stream.

FYI, ag/31384886 addresses the Could not find correct module information warnings mentioned in comment#4.

The fix for R class loading has been merged into M.1 and LB.2.