Paper/patches/server/0399-Wait-for-Async-Tasks-during-shutdown.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Aikar <aikar@aikar.co>
Date: Sun, 10 May 2020 22:16:17 -0400
Subject: [PATCH] Wait for Async Tasks during shutdown

Server.reload() had this logic to give time for tasks to shutdown,
however shutdown did not...

Adds a 5 second grace period for any async tasks to finish and warns
if any are still running after that delay just as reload does.

diff --git a/src/main/java/net/minecraft/server/MinecraftServer.java b/src/main/java/net/minecraft/server/MinecraftServer.java
index a107751a13ccef2729068e9b9822509374d20187..e2b4e7fb68aeaa2a95f3d1dfdd04521746d18a8d 100644
--- a/src/main/java/net/minecraft/server/MinecraftServer.java
+++ b/src/main/java/net/minecraft/server/MinecraftServer.java
@@ -912,6 +912,7 @@ public abstract class MinecraftServer extends ReentrantBlockableEventLoop<TickTa
         // CraftBukkit start
         if (this.server != null) {
             this.server.disablePlugins();
+            this.server.waitForAsyncTasksShutdown(); // Paper
         }
         // CraftBukkit end
         this.getConnection().stop();
diff --git a/src/main/java/org/bukkit/craftbukkit/CraftServer.java b/src/main/java/org/bukkit/craftbukkit/CraftServer.java
index 70dfd93212fb0cb2c1e5e70e0d46e913be6a85e4..b35b3feafbd25d698d3fea463d4bf65b6a09b590 100644
--- a/src/main/java/org/bukkit/craftbukkit/CraftServer.java
+++ b/src/main/java/org/bukkit/craftbukkit/CraftServer.java
@@ -1018,6 +1018,31 @@ public final class CraftServer implements Server {
         org.spigotmc.WatchdogThread.hasStarted = true; // Paper - Disable watchdog early timeout on reload
     }
 
+    // Paper start
+    public void waitForAsyncTasksShutdown() {
+        int pollCount = 0;
+
+        // Wait for at most 5 seconds for plugins to close their threads
+        while (pollCount < 10*5 && getScheduler().getActiveWorkers().size() > 0) {
+            try {
+                Thread.sleep(100);
+            } catch (InterruptedException e) {}
+            pollCount++;
+        }
+
+        List<BukkitWorker> overdueWorkers = getScheduler().getActiveWorkers();
+        for (BukkitWorker worker : overdueWorkers) {
+            Plugin plugin = worker.getOwner();
+            getLogger().log(Level.SEVERE, String.format(
+                "Nag author(s): '%s' of '%s' about the following: %s",
+                plugin.getPluginMeta().getAuthors(),
+                plugin.getPluginMeta().getDisplayName(),
+                "This plugin is not properly shutting down its async tasks when it is being shut down. This task may throw errors during the final shutdown logs and might not complete before process dies."
+            ));
+        }
+    }
+    // Paper end
+
     @Override
     public void reloadData() {
         ReloadCommand.reload(console);