Paper/patches/server/0428-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 d613d9bbd2096788cd0f7e3a8aa901e44a4e25ff..faee8e2a29b4c9cbd62185f401ac7bbd40d8df76 100644
--- a/src/main/java/net/minecraft/server/MinecraftServer.java
+++ b/src/main/java/net/minecraft/server/MinecraftServer.java
@@ -954,6 +954,7 @@ public abstract class MinecraftServer extends ReentrantBlockableEventLoop<TickTa
         // CraftBukkit start
         if (this.server != null) {
             this.server.disablePlugins();
+            this.server.waitForAsyncTasksShutdown(); // Paper
         }
         // CraftBukkit end
         if (this.getConnection() != null) {
diff --git a/src/main/java/org/bukkit/craftbukkit/CraftServer.java b/src/main/java/org/bukkit/craftbukkit/CraftServer.java
index a90b4d062ba602ed63ba11d42898997c4bf672f2..ed4e566cd18de4f58fcbb54cf2b6ed5ce4895d0a 100644
--- a/src/main/java/org/bukkit/craftbukkit/CraftServer.java
+++ b/src/main/java/org/bukkit/craftbukkit/CraftServer.java
@@ -1027,6 +1027,35 @@ 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();
+            String author = "<NoAuthorGiven>";
+            if (plugin.getDescription().getAuthors().size() > 0) {
+                author = plugin.getDescription().getAuthors().get(0);
+            }
+            getLogger().log(Level.SEVERE, String.format(
+                "Nag author: '%s' of '%s' about the following: %s",
+                author,
+                plugin.getDescription().getName(),
+                "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);