Paper/patches/server/0364-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 386f8b825dac6dda253b0c55a3a0eeef5bdca271..0087e8037e2d30d940e6efa886226e59e8daa98f 100644
--- a/src/main/java/net/minecraft/server/MinecraftServer.java
+++ b/src/main/java/net/minecraft/server/MinecraftServer.java
@@ -936,6 +936,7 @@ 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
         if (io.papermc.paper.plugin.PluginInitializerManager.instance().pluginRemapper != null) io.papermc.paper.plugin.PluginInitializerManager.instance().pluginRemapper.shutdown(); // Paper - Plugin remapping
diff --git a/src/main/java/org/bukkit/craftbukkit/CraftServer.java b/src/main/java/org/bukkit/craftbukkit/CraftServer.java
index c6a96664ef914d0da1e24b93da93bad1b4a17716..45799f96978a68a79b4c89e17e9b543dec99a8b1 100644
--- a/src/main/java/org/bukkit/craftbukkit/CraftServer.java
+++ b/src/main/java/org/bukkit/craftbukkit/CraftServer.java
@@ -1024,6 +1024,32 @@ 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."
+            ));
+            if (console.isDebugging()) io.papermc.paper.util.TraceUtil.dumpTraceForThread(worker.getThread(), "still running"); // Paper - Debugging
+        }
+    }
+    // Paper end - Wait for Async Tasks during shutdown
+
     @Override
     public void reloadData() {
         ReloadCommand.reload(this.console);