Paper/patches/server/0374-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 4339a2cd0b2020b673ebdb6902ad0d0a53373a27..d983aec418603a470f640ace139572fd239a3393 100644
--- a/src/main/java/net/minecraft/server/MinecraftServer.java
+++ b/src/main/java/net/minecraft/server/MinecraftServer.java
@@ -930,6 +930,7 @@ public abstract class MinecraftServer extends ReentrantBlockableEventLoop<TickTa
         // CraftBukkit start
         if (this.server != null) {
             this.server.disablePlugins();
+            this.server.waitForAsyncTasksShutdown(); // Paper - Wait for Async Tasks during shutdown
         }
         // 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 0e7cfec27eb76382d4827b62c31e10f118a87dd4..5b41a2c7e26fde4a5e34f2de567d6e1920e51a36 100644
--- a/src/main/java/org/bukkit/craftbukkit/CraftServer.java
+++ b/src/main/java/org/bukkit/craftbukkit/CraftServer.java
@@ -1016,6 +1016,31 @@ public final class CraftServer implements Server {
         org.spigotmc.WatchdogThread.hasStarted = true; // Paper - Disable watchdog early timeout on reload
     }
 
+    // Paper start - Wait for Async Tasks during shutdown
+    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 - Wait for Async Tasks during shutdown
+
     @Override
     public void reloadData() {
         ReloadCommand.reload(this.console);