Bug Report — Server Hang on Player Quit (ConcurrentHashMap Deadlock)

[MrNickax]

The server freezes completely when a player disconnects. Paper’s watchdog detects that the main thread has stopped responding for over 40 seconds.
The thread dump consistently points to DeluxeMenus in NamedHeadHook.onPlayerQuit, where a ConcurrentHashMap.replaceNode() call blocks the main thread.

Paper Version:
git-Paper-42 (MC: 1.21.8)

DeluxeMenus Version:
1.14.2-DEV-208

Stack trace excerpt:
[Paper Watchdog Thread/ERROR]: Current Thread: Server thread
[Paper Watchdog Thread/ERROR]: at java.base/java.util.concurrent.ConcurrentHashMap.replaceNode(ConcurrentHashMap.java:1111)
[Paper Watchdog Thread/ERROR]: at java.base/java.util.concurrent.ConcurrentHashMap.remove(ConcurrentHashMap.java:1102)
[Paper Watchdog Thread/ERROR]: at com.extendedclip.deluxemenus.hooks.playerpoints.NamedHeadHook.onPlayerQuit(NamedHeadHook.java:52)
[Paper Watchdog Thread/ERROR]: at com.destroystokyo.paper.event.executor.asm.generated.GeneratedEventExecutor918.execute(Unknown Source)

[siracozmen01]

Same Problem

[20:19:25] [Paper Watchdog Thread/ERROR]: --- DO NOT REPORT THIS TO PAPER - THIS IS NOT A BUG OR A CRASH - 1.21.8-e05bd09 (MC: 1.21.8) ---
[20:19:25] [Paper Watchdog Thread/ERROR]: The server has not responded for 10 seconds! Creating thread dump
[20:19:25] [Paper Watchdog Thread/ERROR]: ------------------------------
[20:19:25] [Paper Watchdog Thread/ERROR]: Server thread dump (Look for plugins here before reporting to Paper!):
[20:19:25] [Paper Watchdog Thread/ERROR]: ------------------------------
[20:19:25] [Paper Watchdog Thread/ERROR]: Current Thread: Server thread
[20:19:25] [Paper Watchdog Thread/ERROR]: PID: 91 | Suspended: false | Native: false | State: RUNNABLE
[20:19:25] [Paper Watchdog Thread/ERROR]: Stack:
[20:19:25] [Paper Watchdog Thread/ERROR]: java.base@24.0.2/java.util.concurrent.ConcurrentHashMap.replaceNode(ConcurrentHashMap.java:1137)
[20:19:25] [Paper Watchdog Thread/ERROR]: java.base@24.0.2/java.util.concurrent.ConcurrentHashMap.remove(ConcurrentHashMap.java:1116)
[20:19:25] [Paper Watchdog Thread/ERROR]: DeluxeMenus-1.14.2-DEV-208.jar//com.extendedclip.deluxemenus.hooks.NamedHeadHook.onPlayerQuit(NamedHeadHook.java:52)
[20:19:25] [Paper Watchdog Thread/ERROR]: java.base@24.0.2/java.lang.invoke.DirectMethodHandle$Holder.invokeVirtual(DirectMethodHandle$Holder)
[20:19:25] [Paper Watchdog Thread/ERROR]: java.base@24.0.2/java.lang.invoke.LambdaForm$MH/0x000000005c3d4c00.invoke(LambdaForm$MH)
[20:19:25] [Paper Watchdog Thread/ERROR]: java.base@24.0.2/java.lang.invoke.LambdaForm$MH/0x0000000057228c00.invokeExact_MT(LambdaForm$MH)
[20:19:25] [Paper Watchdog Thread/ERROR]: io.papermc.paper.event.executor.MethodHandleEventExecutorTemplate/0x000000005b040000.execute(MethodHandleEventExecutorTemplate.java:46)
[20:19:25] [Paper Watchdog Thread/ERROR]: co.aikar.timings.TimedEventExecutor.execute(TimedEventExecutor.java:80)
[20:19:25] [Paper Watchdog Thread/ERROR]: org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.java:71)
[20:19:25] [Paper Watchdog Thread/ERROR]: io.papermc.paper.plugin.manager.PaperEventManager.callEvent(PaperEventManager.java:61)
[20:19:25] [Paper Watchdog Thread/ERROR]: io.papermc.paper.plugin.manager.PaperPluginManagerImpl.callEvent(PaperPluginManagerImpl.java:131)
[20:19:25] [Paper Watchdog Thread/ERROR]: org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.java:630)
[20:19:25] [Paper Watchdog Thread/ERROR]: net.minecraft.server.players.PlayerList.remove(PlayerList.java:567)
[20:19:25] [Paper Watchdog Thread/ERROR]: net.minecraft.server.players.PlayerList.remove(PlayerList.java:553)
[20:19:25] [Paper Watchdog Thread/ERROR]: net.minecraft.server.network.ServerGamePacketListenerImpl.removePlayerFromWorld(ServerGamePacketListenerImpl.java:2225)
[20:19:25] [Paper Watchdog Thread/ERROR]: net.minecraft.server.network.ServerGamePacketListenerImpl.onDisconnect(ServerGamePacketListenerImpl.java:2203)
[20:19:25] [Paper Watchdog Thread/ERROR]: net.minecraft.network.Connection.handleDisconnection(Connection.java:881)
[20:19:25] [Paper Watchdog Thread/ERROR]: net.minecraft.server.network.ServerConnectionListener.tick(ServerConnectionListener.java:296)
[20:19:25] [Paper Watchdog Thread/ERROR]: net.minecraft.server.MinecraftServer.tickConnection(MinecraftServer.java:1699)
[20:19:25] [Paper Watchdog Thread/ERROR]: net.minecraft.server.dedicated.DedicatedServer.tickConnection(DedicatedServer.java:396)
[20:19:25] [Paper Watchdog Thread/ERROR]: net.minecraft.server.MinecraftServer.tickChildren(MinecraftServer.java:1681)
[20:19:25] [Paper Watchdog Thread/ERROR]: net.minecraft.server.MinecraftServer.tickServer(MinecraftServer.java:1534)
[20:19:25] [Paper Watchdog Thread/ERROR]: net.minecraft.server.MinecraftServer.runServer(MinecraftServer.java:1258)
[20:19:25] [Paper Watchdog Thread/ERROR]: net.minecraft.server.MinecraftServer.lambda$spin$2(MinecraftServer.java:313)
[20:19:25] [Paper Watchdog Thread/ERROR]: net.minecraft.server.MinecraftServer$$Lambda/0x00000000580db9e8.run(Unknown Source)
[20:19:25] [Paper Watchdog Thread/ERROR]: java.base@24.0.2/java.lang.Thread.runWith(Thread.java:1460)
[20:19:25] [Paper Watchdog Thread/ERROR]: java.base@24.0.2/java.lang.Thread.run(Thread.java:1447)
[20:19:25] [Paper Watchdog Thread/ERROR]: ------------------------------
[20:19:25] [Paper Watchdog Thread/ERROR]: --- DO NOT REPORT THIS TO PAPER - THIS IS NOT A BUG OR A CRASH ---
[20:19:25] [Paper Watchdog Thread/ERROR]: ------------------------------

[BlitzOffline]

Hi. Any chance you can create a spark report that runs while this issue happens?

[siracozmen01]

How can I get spark when the server crashes?