Shutdown executors on disable (#6565)

Closes #6446

Author: JRoy

Essentials/src/main/java/com/earth2me/essentials/Essentials.java

@@ -46,6 +46,7 @@
 import com.earth2me.essentials.updatecheck.UpdateChecker;
 import com.earth2me.essentials.userstorage.ModernUserMap;
 import com.earth2me.essentials.utils.FormatUtil;
+import com.earth2me.essentials.utils.PasteUtil;
 import com.earth2me.essentials.utils.VersionUtil;
 import io.papermc.lib.PaperLib;
 import net.ess3.api.Economy;
@@ -587,6 +588,8 @@ public void onDisable() {
         getUsers().shutdown();
 
         EssentialsConfiguration.shutdownExecutor();
+        PasteUtil.shutdownExecutor();
+        getServer().getScheduler().cancelTasks(this);
 
         HandlerList.unregisterAll(this);
     }

Essentials/src/main/java/com/earth2me/essentials/I18n.java

@@ -28,14 +28,15 @@
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Executors;
+import java.util.concurrent.TimeUnit;
 import java.util.function.Function;
 import java.util.logging.Level;
 import java.util.regex.Pattern;
 
 public class I18n implements net.ess3.api.II18n {
     private static final String MESSAGES = "messages";
     private static final Pattern NODOUBLEMARK = Pattern.compile("''");
-    private static final ExecutorService BUNDLE_LOADER_EXECUTOR = Executors.newFixedThreadPool(2);
+    private static volatile ExecutorService BUNDLE_LOADER_EXECUTOR = Executors.newFixedThreadPool(2);
     private static final ResourceBundle NULL_BUNDLE = new ResourceBundle() {
         @SuppressWarnings("NullableProblems")
         public Enumeration<String> getKeys() {
@@ -106,6 +107,29 @@ public void onEnable() {
 
     public void onDisable() {
         instance = null;
+        shutdownExecutor();
+    }
+
+    private static synchronized ExecutorService getExecutor() {
+        if (BUNDLE_LOADER_EXECUTOR == null || BUNDLE_LOADER_EXECUTOR.isShutdown() || BUNDLE_LOADER_EXECUTOR.isTerminated()) {
+            BUNDLE_LOADER_EXECUTOR = Executors.newFixedThreadPool(2);
+        }
+        return BUNDLE_LOADER_EXECUTOR;
+    }
+
+    private static synchronized void shutdownExecutor() {
+        final ExecutorService exec = BUNDLE_LOADER_EXECUTOR;
+        if (exec == null) {
+            return;
+        }
+        exec.shutdown();
+        try {
+            if (!exec.awaitTermination(5, TimeUnit.SECONDS)) {
+                exec.shutdownNow();
+            }
+        } catch (final InterruptedException ignored) {
+            exec.shutdownNow();
+        }
     }
 
     @Override
@@ -124,7 +148,7 @@ private ResourceBundle getBundle(final Locale locale) {
             synchronized (loadingBundles) {
                 if (!loadingBundles.contains(locale)) {
                     loadingBundles.add(locale);
-                    BUNDLE_LOADER_EXECUTOR.submit(() -> {
+                    getExecutor().submit(() -> {
                         blockingLoadBundle(locale);
                         synchronized (loadingBundles) {
                             loadingBundles.remove(locale);

Essentials/src/main/java/com/earth2me/essentials/utils/PasteUtil.java

@@ -16,12 +16,13 @@
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Executors;
+import java.util.concurrent.TimeUnit;
 import java.util.zip.GZIPOutputStream;
 
 public final class PasteUtil {
     private static final String PASTE_URL = "https://pastes.dev/";
     private static final String PASTE_UPLOAD_URL = "https://api.pastes.dev/post";
-    private static final ExecutorService PASTE_EXECUTOR_SERVICE = Executors.newSingleThreadExecutor();
+    private static volatile ExecutorService PASTE_EXECUTOR_SERVICE = Executors.newSingleThreadExecutor();
     private static final Gson GSON = new Gson();
 
     private PasteUtil() {
@@ -35,7 +36,7 @@ private PasteUtil() {
      */
     public static CompletableFuture<PasteResult> createPaste(List<PasteFile> pages) {
         final CompletableFuture<PasteResult> future = new CompletableFuture<>();
-        PASTE_EXECUTOR_SERVICE.submit(() -> {
+        getExecutor().submit(() -> {
             try {
                 final HttpURLConnection connection = (HttpURLConnection) new URL(PASTE_UPLOAD_URL).openConnection();
                 connection.setRequestMethod("POST");
@@ -81,6 +82,28 @@ public static CompletableFuture<PasteResult> createPaste(List<PasteFile> pages)
         return future;
     }
 
+    private static synchronized ExecutorService getExecutor() {
+        if (PASTE_EXECUTOR_SERVICE == null || PASTE_EXECUTOR_SERVICE.isShutdown() || PASTE_EXECUTOR_SERVICE.isTerminated()) {
+            PASTE_EXECUTOR_SERVICE = Executors.newSingleThreadExecutor();
+        }
+        return PASTE_EXECUTOR_SERVICE;
+    }
+
+    public static synchronized void shutdownExecutor() {
+        final ExecutorService exec = PASTE_EXECUTOR_SERVICE;
+        if (exec == null) {
+            return;
+        }
+        exec.shutdown();
+        try {
+            if (!exec.awaitTermination(5, TimeUnit.SECONDS)) {
+                exec.shutdownNow();
+            }
+        } catch (final InterruptedException ignored) {
+            exec.shutdownNow();
+        }
+    }
+
     public static class PasteFile {
         private final String name;
         private final String contents;