EDT deadlock in MacDockDelegate.updateRecentProjectsMenu → CMenu.delItem → AWTThreading on macOS

[mdproctor]

Summary

IntelliJ IDEA 2026.1 (IU-261.24374.151) freezes repeatedly on macOS due to an EDT deadlock in MacDockDelegate.updateRecentProjectsMenu. The EDT blocks for 33-34 seconds each time, requiring a force quit.

14 freeze dumps in 10 days, all with identical stack trace.

Environment

• macOS (Apple Silicon)
• IntelliJ IDEA 2026.1 Ultimate (IU-261.24374.151)
• JBR 21
• Multiple projects open (lifecycle-managed via MCP plugin — projects open/close frequently)

Stack trace (from freeze report)

MacDockDelegate$updateRecentProjectsMenu$2.invokeSuspend 33600ms
  java.awt.Menu.removeAll 33600ms
    java.awt.Menu.remove 33600ms
      sun.lwawt.macosx.CMenu.delItem 33600ms
        sun.awt.AWTThreading.executeWaitToolkit 33600ms
          sun.awt.AWTThreading.execute 33600ms
            java.util.concurrent.LinkedBlockingQueue.take 33600ms
              java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await 33600ms
                java.util.concurrent.ForkJoinPool.managedBlock 33600ms
                  java.util.concurrent.locks.LockSupport.park 33600ms

The EDT dispatches the coroutine MacDockDelegate.updateRecentProjectsMenu, which calls Menu.removeAll() → CMenu.delItem(). This crosses into native AppKit via AWTThreading.executeWaitToolkit, which blocks waiting for the toolkit thread — but the toolkit thread never responds, causing a 33+ second deadlock.

Reproduction

Occurs repeatedly without user interaction — likely triggered by project open/close events that update the recent projects list. With lifecycle management cycling projects through active → dormant → closed states, the recent projects menu gets updated frequently.

Freeze dump directory listing

All 14 freeze reports have identical root cause:

threadDumps-freeze-20260628-042003
threadDumps-freeze-20260629-171225
threadDumps-freeze-20260630-093516
threadDumps-freeze-20260630-114146
threadDumps-freeze-20260705-141403
threadDumps-freeze-20260705-235344
threadDumps-freeze-20260706-042610
threadDumps-freeze-20260706-111733
threadDumps-freeze-20260706-164717
threadDumps-freeze-20260706-175710
threadDumps-freeze-20260707-190348
threadDumps-freeze-20260707-210538
threadDumps-freeze-20260708-004818

Notes

• -Dsun.java2d.metal=false is unlikely to help — this is an AWT/AppKit thread bridge deadlock, not a rendering issue
• The freeze occurs during native menu manipulation (CMenu.delItem), not during rendering
• Reducing the number of recent projects or the frequency of project open/close events may reduce occurrence