From b7725a7764215b33382c502634a48bb647dc0cd9 Mon Sep 17 00:00:00 2001
From: Andrew Steinborn <git@steinborn.me>
Date: Tue, 28 Aug 2018 21:27:03 -0400
Subject: [PATCH] More sane shutdown code.

---
 .../velocitypowered/proxy/scheduler/VelocityScheduler.java | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/proxy/src/main/java/com/velocitypowered/proxy/scheduler/VelocityScheduler.java b/proxy/src/main/java/com/velocitypowered/proxy/scheduler/VelocityScheduler.java
index 3e87ab911..6e10807e3 100644
--- a/proxy/src/main/java/com/velocitypowered/proxy/scheduler/VelocityScheduler.java
+++ b/proxy/src/main/java/com/velocitypowered/proxy/scheduler/VelocityScheduler.java
@@ -12,6 +12,7 @@ import com.velocitypowered.api.scheduler.TaskStatus;
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
 
+import java.util.Collection;
 import java.util.HashSet;
 import java.util.IdentityHashMap;
 import java.util.concurrent.*;
@@ -41,7 +42,11 @@ public class VelocityScheduler implements Scheduler {
     }
 
     public boolean shutdown() throws InterruptedException {
-        for (ScheduledTask task : ImmutableList.copyOf(tasksByPlugin.values())) {
+        Collection<ScheduledTask> terminating;
+        synchronized (tasksByPlugin) {
+            terminating = ImmutableList.copyOf(tasksByPlugin.values());
+        }
+        for (ScheduledTask task : terminating) {
             task.cancel();
         }
         timerExecutionService.shutdown();