Bug: Server hang/Watchdog trigger during command parsing (FancyNpcs 2.9.1)

[spygamingog]

In which plugin has the error occurred?

FancyNpcs

What happened?

I was clicking an NPC.

My server is experiencing significant lag spikes (10+ seconds) that trigger the Paper Watchdog. The thread dump consistently points to FancyNpcs blocking the main server thread during command execution/parsing. And caused my server crash

Server Version: Paper 1.21.1 (Build 1.21.1-69-94d0c97) Plugin Version: 2.9.1 Java Version: 21.0.9

In which software has the error occurred?

Paper

Plugin version

2.9.1

Server version

1.21.11

Relevant log output

[17:08:18 ERROR]: Current Thread: Server thread
[17:08:18 ERROR]:       PID: 40 | Suspended: false | Native: false | State: RUNNABLE
[17:08:18 ERROR]:       Stack:
[17:08:18 ERROR]:               java.base@21.0.9/java.util.concurrent.CompletableFuture$UniCompose.tryFire(CompletableFuture.java:1138)
[17:08:18 ERROR]:               java.base@21.0.9/java.util.concurrent.CompletableFuture$Completion.run(CompletableFuture.java:482)
[17:08:18 ERROR]:               FancyNpcs-2.9.1.jar//de.oliver.cloud.execution.ExecutionCoordinatorImpl$NonSchedulingExecutor.execute(ExecutionCoordinatorImpl.java:53)
[17:08:18 ERROR]:               java.base@21.0.9/java.util.concurrent.CompletableFuture.uniComposeStage(CompletableFuture.java:1184)
[17:08:18 ERROR]:               java.base@21.0.9/java.util.concurrent.CompletableFuture.thenComposeAsync(CompletableFuture.java:2352)
[17:08:18 ERROR]:               FancyNpcs-2.9.1.jar//de.oliver.cloud.CommandTree.lambda$parseCommand$4(CommandTree.java:306)
[17:08:18 ERROR]:               FancyNpcs-2.9.1.jar//de.oliver.cloud.CommandTree$$Lambda/0x000000c803a886e8.apply(Unknown Source)
[17:08:18 ERROR]:               java.base@21.0.9/java.util.concurrent.CompletableFuture.uniComposeStage(CompletableFuture.java:1187)
[17:08:18 ERROR]:               java.base@21.0.9/java.util.concurrent.CompletableFuture.thenCompose(CompletableFuture.java:2341)
[17:08:18 ERROR]:               FancyNpcs-2.9.1.jar//de.oliver.cloud.CommandTree.parseCommand(CommandTree.java:289)
[17:08:18 ERROR]:               FancyNpcs-2.9.1.jar//de.oliver.cloud.CommandTree.parseDirect(CommandTree.java:205)
[17:08:18 ERROR]:               FancyNpcs-2.9.1.jar//de.oliver.cloud.CommandTree.lambda$parse$0(CommandTree.java:180)
[17:08:18 ERROR]:               FancyNpcs-2.9.1.jar//de.oliver.cloud.CommandTree$$Lambda/0x000000c803a85a30.get(Unknown Source)
[17:08:18 ERROR]:               java.base@21.0.9/java.util.concurrent.CompletableFuture$AsyncSupply.run(CompletableFuture.java:1768)
[17:08:18 ERROR]:               FancyNpcs-2.9.1.jar//de.oliver.cloud.execution.ExecutionCoordinatorImpl$NonSchedulingExecutor.execute(ExecutionCoordinatorImpl.java:53)
[17:08:18 ERROR]:               java.base@21.0.9/java.util.concurrent.CompletableFuture.asyncSupplyStage(CompletableFuture.java:1782)
[17:08:18 ERROR]:               java.base@21.0.9/java.util.concurrent.CompletableFuture.supplyAsync(CompletableFuture.java:2005)
[17:08:18 ERROR]:               FancyNpcs-2.9.1.jar//de.oliver.cloud.util.CompletableFutures.scheduleOn(CompletableFutures.java:70)
[17:08:18 ERROR]:               FancyNpcs-2.9.1.jar//de.oliver.cloud.CommandTree.parse(CommandTree.java:180)
[17:08:18 ERROR]:               FancyNpcs-2.9.1.jar//de.oliver.cloud.execution.ExecutionCoordinatorImpl.coordinateExecution(ExecutionCoordinatorImpl.java:98)
[17:08:18 ERROR]:               FancyNpcs-2.9.1.jar//de.oliver.cloud.StandardCommandExecutor.executeCommand(StandardCommandExecutor.java:91)