LSPDocumentAbstractHandler.setEnabled can cause an UI freeze #1331
Description
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 [email protected]/jdk.internal.misc.Unsafe.park(Native Method)
at [email protected]/java.util.concurrent.locks.LockSupport.parkNanos(LockSupport.java:252)
at [email protected]/java.util.concurrent.CompletableFuture$Signaller.block(CompletableFuture.java:1866)
at [email protected]/java.util.concurrent.ForkJoinPool.unmanagedBlock(ForkJoinPool.java:3463)
at [email protected]/java.util.concurrent.ForkJoinPool.managedBlock(ForkJoinPool.java:3434)
at [email protected]/java.util.concurrent.CompletableFuture.timedGet(CompletableFuture.java:1939)
at [email protected]/java.util.concurrent.CompletableFuture.get(CompletableFuture.java:2095)
at org.eclipse.lsp4e.internal.LSPDocumentAbstractHandler$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 [email protected]/java.util.stream.MatchOps$1MatchSink.accept(MatchOps.java:90)
at [email protected]/java.util.AbstractList$RandomAccessSpliterator.tryAdvance(AbstractList.java:706)
at [email protected]/java.util.stream.ReferencePipeline.forEachWithCancel(ReferencePipeline.java:129)
at [email protected]/java.util.stream.AbstractPipeline.copyIntoWithCancel(AbstractPipeline.java:527)
at [email protected]/java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:513)
at [email protected]/java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:499)
at [email protected]/java.util.stream.MatchOps$MatchOp.evaluateSequential(MatchOps.java:230)
at [email protected]/java.util.stream.MatchOps$MatchOp.evaluateSequential(MatchOps.java:196)
at [email protected]/java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234)
at [email protected]/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 [email protected]/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at [email protected]/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.