SWTException: Invalid thread access in MavenConsoleLineTracker.launchRemoteJavaApp

[khroolick]

Body:

Summary

MavenConsoleLineTracker#launchRemoteJavaApp invokes DebugUITools.launch(...) from a non-UI thread (a ConsolePatternMatcher$MatchJob worker). DebugUITools.launch eventually calls Display.getShells(), which enforces UI-thread access, so the launch fails with SWTException: Invalid thread access. The Maven build itself succeeds, but the auto-attach of the remote Java debugger for a forked JVM (e.g. Surefire <debug>true</debug>, mvnDebug, or -Dmaven.surefire.debug) is aborted and an error is logged.

Environment

• Eclipse IDE for Enterprise Java and Web Developers 4.40.0.20260604-0652 (2026-06)
• Product: org.eclipse.epp.package.jee.product
• OS: Windows 10/11 x86_64 (win32/win32/x86_64), locale en_GB
• Java: 21.0.12 (Eclipse Adoptium)
• m2e:
  • org.eclipse.m2e.feature.feature.group 2.10.200.20260602-0749
  • org.eclipse.m2e.sdk.feature.feature.group 2.11.1.20260602-0814
  • org.eclipse.m2e.pde.feature.feature.group 2.3.700.20260602-0814
  • org.eclipse.m2e.lemminx.feature.feature.group 2.6.101.20250727-0612
  • org.eclipse.m2e.logback.feature.feature.group 2.7.200.20251018-1026
• Workspace: file:/S:/_workspaces/distribution/

Steps to reproduce

1. In Eclipse, run a Maven build that forks a JVM with a debug port (e.g. Roomlynx service tests with Surefire <debug>true</debug>, mvnDebug, or -Dmaven.surefire.debug).
2. Wait for the Maven console to print the line recognized by MavenConsoleLineTracker (e.g. Listening for transport dt_socket at address: <port>).
3. launchRemoteJavaApp is called from the ConsolePatternMatcher$MatchJob worker thread.

Expected result

A remote Java application debug configuration is created and launched; Eclipse attaches the debugger to the forked JVM.

Actual result

The launch is aborted and an SWTException: Invalid thread access error is logged. The Maven build continues, but the debugger does not attach.

Stack trace

org.eclipse.swt.SWTException: Invalid thread access
	at org.eclipse.swt.SWT.error(SWT.java:4922)
	at org.eclipse.swt.SWT.error(SWT.java:4837)
	at org.eclipse.swt.SWT.error(SWT.java:4808)
	at org.eclipse.swt.widgets.Display.error(Display.java:1324)
	at org.eclipse.swt.widgets.Display.checkDevice(Display.java:875)
	at org.eclipse.swt.widgets.Display.getShells(Display.java:2318)
	at org.eclipse.ui.internal.progress.ProgressManagerUtil.getModalShellExcluding(ProgressManagerUtil.java:410)
	...
	at org.eclipse.debug.ui.DebugUITools.launch(DebugUITools.java:...)
	at org.eclipse.m2e.internal.launch.MavenConsoleLineTracker.launchRemoteJavaApp(MavenConsoleLineTracker.java:332)
	at org.eclipse.m2e.internal.launch.MavenConsoleLineTracker.lineAppended(MavenConsoleLineTracker.java:156)
	at org.eclipse.debug.internal.ui.views.console.ConsolePatternMatcher$MatchJob.run(ConsolePatternMatcher.java:...)
	at org.eclipse.core.internal.jobs.Worker.run(Worker.java:...)

Possible fix

Wrap the DebugUITools.launch(...) call in Display.getDefault().asyncExec(...) (or otherwise ensure it runs on the SWT UI thread) before invoking any UI/debug-launch API.

[HannesWell]

I can confirm that this can happen, but for me it seems not to happen always.
But anyway, do you want to create a PR with your proposed solution?

[khroolick]

I've installed the local build, and it works. Eclipse attaches its debugger without any errors now.

[khroolick]

@HannesWell could you take a look and help me apply this fix?