From 16b349057647d272d25767ab67546bdef5ad275b Mon Sep 17 00:00:00 2001
From: JoJoDeveloping <jojohostert@gmail.com>
Date: Tue, 28 Aug 2018 09:25:50 +0200
Subject: [PATCH] #2520: Fix ConcurrentModificationException when tasks are
 cancelled during shutdown

---
 .../java/net/md_5/bungee/scheduler/BungeeScheduler.java    | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/proxy/src/main/java/net/md_5/bungee/scheduler/BungeeScheduler.java b/proxy/src/main/java/net/md_5/bungee/scheduler/BungeeScheduler.java
index 1dc1cc66..fd0dabcf 100644
--- a/proxy/src/main/java/net/md_5/bungee/scheduler/BungeeScheduler.java
+++ b/proxy/src/main/java/net/md_5/bungee/scheduler/BungeeScheduler.java
@@ -62,9 +62,12 @@ public class BungeeScheduler implements TaskScheduler
     public int cancel(Plugin plugin)
     {
         Set<ScheduledTask> toRemove = new HashSet<>();
-        for ( ScheduledTask task : tasksByPlugin.get( plugin ) )
+        synchronized ( lock )
         {
-            toRemove.add( task );
+            for ( ScheduledTask task : tasksByPlugin.get( plugin ) )
+            {
+                toRemove.add( task );
+            }
         }
         for ( ScheduledTask task : toRemove )
         {