LSPDocumentAbstractHandler.setEnabled can cause an UI freeze

We have observed the following UI freeze caused by LSP4E:

!ENTRY org.eclipse.ui.monitoring 2 0 2025-07-21 10:01:26.475
!MESSAGE UI freeze of 0.36s at 10:01:26.097
!SUBENTRY 1 org.eclipse.ui.monitoring 1 0 2025-07-21 10:01:26.475
!MESSAGE Sample at 10:01:26.298 (+0.201s)
Thread 'main' tid=1 (TIMED_WAITING)
!STACK 0
Stack Trace
	at java.base@17.0.5/jdk.internal.misc.Unsafe.park(Native Method)
	at java.base@17.0.5/java.util.concurrent.locks.LockSupport.parkNanos(LockSupport.java:252)
	at java.base@17.0.5/java.util.concurrent.CompletableFuture$Signaller.block(CompletableFuture.java:1866)
	at java.base@17.0.5/java.util.concurrent.ForkJoinPool.unmanagedBlock(ForkJoinPool.java:3463)
	at java.base@17.0.5/java.util.concurrent.ForkJoinPool.managedBlock(ForkJoinPool.java:3434)
	at java.base@17.0.5/java.util.concurrent.CompletableFuture.timedGet(CompletableFuture.java:1939)
	at java.base@17.0.5/java.util.concurrent.CompletableFuture.get(CompletableFuture.java:2095)
	at org.eclipse.lsp4e.internal.LSPDocumentAbstractHandler$LanguageServerDocumentHandlerExecutor.matches(LSPDocumentAbstractHandler.java:69)
	at org.eclipse.lsp4e.internal.LSPDocumentAbstractHandler$LanguageServerDocumentHandlerExecutor.lambda$0(LSPDocumentAbstractHandler.java:59)
	at org.eclipse.lsp4e.internal.LSPDocumentAbstractHandler$LanguageServerDocumentHandlerExecutor$$Lambda$1693/0x0000000801a61638.test(Unknown Source)
	at java.base@17.0.5/java.util.stream.MatchOps$1MatchSink.accept(MatchOps.java:90)
	at java.base@17.0.5/java.util.AbstractList$RandomAccessSpliterator.tryAdvance(AbstractList.java:706)
	at java.base@17.0.5/java.util.stream.ReferencePipeline.forEachWithCancel(ReferencePipeline.java:129)
	at java.base@17.0.5/java.util.stream.AbstractPipeline.copyIntoWithCancel(AbstractPipeline.java:527)
	at java.base@17.0.5/java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:513)
	at java.base@17.0.5/java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:499)
	at java.base@17.0.5/java.util.stream.MatchOps$MatchOp.evaluateSequential(MatchOps.java:230)
	at java.base@17.0.5/java.util.stream.MatchOps$MatchOp.evaluateSequential(MatchOps.java:196)
	at java.base@17.0.5/java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234)
	at java.base@17.0.5/java.util.stream.ReferencePipeline.anyMatch(ReferencePipeline.java:632)
	at org.eclipse.lsp4e.internal.LSPDocumentAbstractHandler$LanguageServerDocumentHandlerExecutor.anyMatching(LSPDocumentAbstractHandler.java:59)
	at org.eclipse.lsp4e.internal.LSPDocumentAbstractHandler.setEnabled(LSPDocumentAbstractHandler.java:123)
	at org.eclipse.lsp4e.internal.LSPDocumentAbstractHandler.setEnabled(LSPDocumentAbstractHandler.java:113)
	at org.eclipse.lsp4e.operations.rename.LSPRenameHandler.setEnabled(LSPRenameHandler.java:74)
	at org.eclipse.ui.internal.handlers.HandlerProxy.setEnabled(HandlerProxy.java:223)
	at org.eclipse.ui.internal.handlers.E4HandlerProxy.setEnabled(E4HandlerProxy.java:134)
	at jdk.internal.reflect.GeneratedMethodAccessor10.invoke(Unknown Source)
	at java.base@17.0.5/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.base@17.0.5/java.lang.reflect.Method.invoke(Method.java:568)
	at org.eclipse.e4.core.internal.di.MethodRequestor.execute(MethodRequestor.java:56)
	at org.eclipse.e4.core.internal.di.InjectorImpl.invokeUsingClass(InjectorImpl.java:299)
	at org.eclipse.e4.core.internal.di.InjectorImpl.invoke(InjectorImpl.java:233)
	at org.eclipse.e4.core.contexts.ContextInjectionFactory.invoke(ContextInjectionFactory.java:174)
	at org.eclipse.e4.core.commands.internal.HandlerServiceHandler.setEnabled(HandlerServiceHandler.java:91)
	at org.eclipse.core.commands.Command.setEnabled(Command.java:856)
	at org.eclipse.ui.menus.CommandContributionItem.isEnabled(CommandContributionItem.java:932)
	at org.eclipse.ui.menus.CommandContributionItem.updateMenuItem(CommandContributionItem.java:536)
	at org.eclipse.ui.menus.CommandContributionItem.update(CommandContributionItem.java:486)
	at org.eclipse.jface.action.MenuManager.update(MenuManager.java:857)
	at org.eclipse.jface.action.MenuManager.update(MenuManager.java:857)
	at org.eclipse.ui.internal.Workbench.updateActiveWorkbenchWindowMenuManager(Workbench.java:3246)
	at org.eclipse.ui.internal.Workbench.lambda$0(Workbench.java:3228)
	at org.eclipse.ui.internal.Workbench$$Lambda$397/0x0000000801196540.bindingManagerChanged(Unknown Source)
	at org.eclipse.jface.bindings.BindingManager.fireBindingManagerChanged(BindingManager.java:896)
	at org.eclipse.jface.bindings.BindingManager.setActiveBindings(BindingManager.java:2178)
	at org.eclipse.jface.bindings.BindingManager.recomputeBindings(BindingManager.java:1737)
	at org.eclipse.jface.bindings.BindingManager.contextManagerChanged(BindingManager.java:693)
	at org.eclipse.core.commands.contexts.ContextManager.fireContextManagerChanged(ContextManager.java:164)
	at org.eclipse.core.commands.contexts.ContextManager.setEventCaching(ContextManager.java:323)
	at org.eclipse.core.commands.contexts.ContextManager.deferUpdates(ContextManager.java:85)
	at org.eclipse.e4.ui.internal.workbench.PartServiceImpl.activate(PartServiceImpl.java:787)

Even though the handler waits for a max of 50ms, there are plenty of subclasses of LSPDocumentAbstractHandler, so calling setEnable on several of these these when opening/activating an editor (or starting the workbench) can cumulate to a noticeable UI freeze.

Since the code is prepared to return false and enable the handler asynchronously when the completableFuture finishes, I think we can eliminate the UI freeze by lowering the timeout to lower number, for example 5ms.

Start in LSPDocumentAbstractHandler.java, especially setEnabled and LanguageServerDocumentHandlerExecutor.matches/anyMatching around the CompletableFuture wait shown in the stack trace. Inspect the handler subclasses and existing tests, then verify that the enabled-state check no longer causes cumulative UI blocking while asynchronous completion still updates the handler correctly.