Paper/patches/server/0417-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 407cfb88d3a6c9c699ca42df2642d9f6fad87cbd..df40ab29f928fa31ccedb9afb64da7e193a8d1f7 100644
--- a/src/main/java/net/minecraft/server/MinecraftServer.java
+++ b/src/main/java/net/minecraft/server/MinecraftServer.java
@@ -907,6 +907,7 @@ 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 7859cda59999ab1b7b22af6cd682c1afe8a7029f..586415d732bf9a1bb8ec2227b447f64912d3b4e4 100644
--- a/src/main/java/org/bukkit/craftbukkit/CraftServer.java
+++ b/src/main/java/org/bukkit/craftbukkit/CraftServer.java
@@ -1009,6 +1009,35 @@ 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);