Searching tests cause freezes in big multi-module projects with junit 5

related to #1203

You can use my open source project to reproduce it -- it's contain dozen maven modules, 2 millions loc, 9000 junit4 and junit5 tests, and already preconfigured and optimized with dev container (vscode and java tools inside, it also include instruction to setup and first run command):

• https://github.com/magefree/mage

Main problem:

• if you run tests from the root module (mage-tests) -- you will see popup "searching tests" message -- it's take 100-150+ seconds on any runs (cold and hot);
• single tests or small "folders" starting fast;

Dump collect by command (call it while "searching tests"):

• jstack $(pgrep -f equinox.launcher) > jdtls-hang.txt

After some dumps research it was found the root of the problem: JUnit5TestFinder process. It's try to scan and construct full AST tree and fail on big amount of files. JUnit4TestFinder works too fast and miss from the dumps.

JUnit5TestFinder.internalIsTest()

WeakHashSet.cleanupGarbageCollectedValues
→ WeakHashSet.add
→ DeduplicationUtil.toString (locked WeakHashSet)
→ SearchableEnvironment.findType
→ ...

dump 1 example:

"ForkJoinPool.commonPool-worker-5" #337 [2445] daemon prio=5 os_prio=0 cpu=22747.59ms elapsed=184.51s tid=0x0000ffff140010f0 nid=2445 runnable
   java.lang.Thread.State: RUNNABLE
	at org.eclipse.jdt.internal.compiler.parser.Scanner.jumpOverMethodBody(Scanner.java:2247)
	at org.eclipse.jdt.internal.compiler.parser.Scanner.getNextToken0(Scanner.java:1286)
	at org.eclipse.jdt.internal.compiler.parser.Parser.dietParse(Parser.java:10308)
	at org.eclipse.jdt.internal.compiler.Compiler.accept(Compiler.java:220)
	at org.eclipse.jdt.core.dom.CompilationUnitResolver.accept(CompilationUnitResolver.java:230)
	- locked <0x00000007aadbb700> (a org.eclipse.jdt.core.dom.CompilationUnitResolver)
	at org.eclipse.jdt.internal.compiler.lookup.LookupEnvironment.askForType(LookupEnvironment.java:434)
	...
	at org.eclipse.jdt.internal.compiler.lookup.ClassScope.connectTypeHierarchy(ClassScope.java:1394)
	at org.eclipse.jdt.internal.compiler.lookup.LookupEnvironment.completeTypeBindings(LookupEnvironment.java:612)
	at org.eclipse.jdt.internal.compiler.Compiler.internalBeginToCompile(Compiler.java:787)
	at org.eclipse.jdt.core.dom.CompilationUnitResolver.resolve(CompilationUnitResolver.java:1240)
	at org.eclipse.jdt.core.dom.ASTParser.internalCreateASTCached(ASTParser.java:1412)
	at org.eclipse.jdt.core.dom.ASTParser.createAST(ASTParser.java:933)
	at org.eclipse.jdt.internal.junit.launcher.JUnit5TestFinder.internalIsTest(JUnit5TestFinder.java:271)
	at org.eclipse.jdt.internal.junit.launcher.JUnit5TestFinder.findTestsInContainer(JUnit5TestFinder.java:221)
	at com.microsoft.java.test.plugin.searcher.JUnit5TestSearcher.findTestItemsInContainer(JUnit5TestSearcher.java:130)
	at com.microsoft.java.test.plugin.util.TestSearchUtils.findTestPackagesAndTypes(TestSearchUtils.java:169)
	at com.microsoft.java.test.plugin.handler.TestDelegateCommandHandler.executeCommand(TestDelegateCommandHandler.java:61)

dump 2 example:

"ForkJoinPool.commonPool-worker-8" #340 [2448] daemon prio=5 os_prio=0 cpu=22085.22ms elapsed=184.51s tid=0x0000fffeec001b30 nid=2448 runnable
   java.lang.Thread.State: RUNNABLE
	at org.eclipse.jdt.internal.compiler.parser.AbstractCommentParser.commentParse(AbstractCommentParser.java:225)
	at org.eclipse.jdt.internal.compiler.parser.JavadocParser.checkDeprecation(JavadocParser.java:117)
	...
	at org.eclipse.jdt.internal.compiler.lookup.SourceTypeBinding.methods(SourceTypeBinding.java:1770)
	at org.eclipse.jdt.internal.compiler.lookup.MethodVerifier.computeInheritedMethods(MethodVerifier.java:543)
	at org.eclipse.jdt.internal.compiler.lookup.MethodVerifier.verify(MethodVerifier.java:1012)
	at org.eclipse.jdt.internal.compiler.lookup.SourceTypeBinding.verifyMethods(SourceTypeBinding.java:2830)
	at org.eclipse.jdt.internal.compiler.lookup.CompilationUnitScope.verifyMethods(CompilationUnitScope.java:1025)
	at org.eclipse.jdt.core.dom.CompilationUnitResolver.resolve(CompilationUnitResolver.java:1307)
	at org.eclipse.jdt.core.dom.ASTParser.createAST(ASTParser.java:933)
	at org.eclipse.jdt.internal.junit.launcher.JUnit5TestFinder.internalIsTest(JUnit5TestFinder.java:271)
	at org.eclipse.jdt.internal.junit.launcher.JUnit5TestFinder.findTestsInContainer(JUnit5TestFinder.java:221)
	at com.microsoft.java.test.plugin.searcher.JUnit5TestSearcher.findTestItemsInContainer(JUnit5TestSearcher.java:130)
	at com.microsoft.java.test.plugin.util.TestSearchUtils.findTestPackagesAndTypes(TestSearchUtils.java:169)
	at com.microsoft.java.test.plugin.handler.TestDelegateCommandHandler.executeCommand(TestDelegateCommandHandler.java:61)

dump 3 example

"ForkJoinPool.commonPool-worker-5" #337 [2445] daemon prio=5 os_prio=0 cpu=52162.83ms elapsed=609.17s tid=0x0000ffff140010f0 nid=2445 runnable
   java.lang.Thread.State: RUNNABLE
	at org.eclipse.jdt.internal.core.util.WeakHashSet.cleanupGarbageCollectedValues(WeakHashSet.java:123)
	at org.eclipse.jdt.internal.core.util.WeakHashSet.add(WeakHashSet.java:78)
	at org.eclipse.jdt.internal.core.util.DeduplicationUtil.toString(DeduplicationUtil.java:46)
	- locked <0x000000070209e980> (a org.eclipse.jdt.internal.core.util.WeakHashSet)
	at org.eclipse.jdt.internal.core.SearchableEnvironment.findType(SearchableEnvironment.java:576)
	at org.eclipse.jdt.internal.compiler.lookup.LookupEnvironment.askForType(LookupEnvironment.java:386)
	at org.eclipse.jdt.internal.compiler.lookup.MethodVerifier.computeInheritedMethods(MethodVerifier.java:543)
	at org.eclipse.jdt.internal.compiler.lookup.MethodVerifier.verify(MethodVerifier.java:1012)
	at org.eclipse.jdt.internal.compiler.lookup.SourceTypeBinding.verifyMethods(SourceTypeBinding.java:2830)
	at org.eclipse.jdt.core.dom.CompilationUnitResolver.resolve(CompilationUnitResolver.java:1307)
	at org.eclipse.jdt.core.dom.ASTParser.createAST(ASTParser.java:933)
	at org.eclipse.jdt.internal.junit.launcher.JUnit5TestFinder.internalIsTest(JUnit5TestFinder.java:271)
	at org.eclipse.jdt.internal.junit.launcher.JUnit5TestFinder.findTestsInContainer(JUnit5TestFinder.java:221)
	at com.microsoft.java.test.plugin.searcher.JUnit5TestSearcher.findTestItemsInContainer(JUnit5TestSearcher.java:130)
	at com.microsoft.java.test.plugin.util.TestSearchUtils.findTestPackagesAndTypes(TestSearchUtils.java:169)

Reproduce el retraso con el proyecto mage enlazado y el comando de búsqueda de tests descrito. Empieza en JUnit5TestSearcher.findTestItemsInContainer y TestSearchUtils.findTestPackagesAndTypes, y después inspecciona la ruta JUnit5TestFinder.internalIsTest junto con los dumps proporcionados. Se considera terminado cuando el descubrimiento de tests del módulo raíz ya no se congela durante minutos, mientras el descubrimiento de un solo test y de carpetas pequeñas sigue funcionando.