diff --git a/sources/src/main/java/io/akarin/api/internal/utils/ReentrantSpinningDebugLock.java b/sources/src/main/java/io/akarin/api/internal/utils/ReentrantSpinningDebugLock.java
deleted file mode 100644
index 4e5c85786..000000000
--- a/sources/src/main/java/io/akarin/api/internal/utils/ReentrantSpinningDebugLock.java
+++ /dev/null
@@ -1,30 +0,0 @@
-package io.akarin.api.internal.utils;
-
-import java.util.concurrent.atomic.AtomicBoolean;
-
-public class ReentrantSpinningDebugLock extends ReentrantSpinningLock {
-    private final AtomicBoolean singleLock = new AtomicBoolean(false);
-    private long heldThreadId = 0;
-    private int reentrantLocks = 0;
-    public StackTraceElement[] tStackTraceElements;
-
-    public void lock() {
-        long currentThreadId = Thread.currentThread().getId();
-        if (heldThreadId == currentThreadId) {
-            reentrantLocks++;
-        } else {
-            while (!singleLock.compareAndSet(false, true)) ; // In case acquire one lock concurrently
-            heldThreadId = currentThreadId;
-        }
-        tStackTraceElements = Thread.currentThread().getStackTrace();
-    }
-    
-    public void unlock() {
-        if (reentrantLocks == 0) {
-            heldThreadId = 0;
-            singleLock.set(false);
-        } else {
-            --reentrantLocks;
-        }
-    }
-}
diff --git a/sources/src/main/java/io/akarin/api/internal/utils/thread/OpenExecutionException.java b/sources/src/main/java/io/akarin/api/internal/utils/thread/OpenExecutionException.java
new file mode 100644
index 000000000..215952436
--- /dev/null
+++ b/sources/src/main/java/io/akarin/api/internal/utils/thread/OpenExecutionException.java
@@ -0,0 +1,7 @@
+package io.akarin.api.internal.utils.thread;
+
+import java.util.concurrent.ExecutionException;
+
+public class OpenExecutionException extends ExecutionException {
+    private static final long serialVersionUID = 7830266012832686185L;
+}
diff --git a/sources/src/main/java/io/akarin/api/internal/utils/thread/SuspendableAbstractExecutorService.java b/sources/src/main/java/io/akarin/api/internal/utils/thread/SuspendableAbstractExecutorService.java
deleted file mode 100644
index fe249187d..000000000
--- a/sources/src/main/java/io/akarin/api/internal/utils/thread/SuspendableAbstractExecutorService.java
+++ /dev/null
@@ -1,318 +0,0 @@
-/*
- * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
- *
- *
- *
- *
- *
- *
- *
- *
- *
- *
- *
- *
- *
- *
- *
- *
- *
- *
- *
- *
- */
-
-/*
- *
- *
- *
- *
- *
- * Written by Doug Lea with assistance from members of JCP JSR-166
- * Expert Group and released to the public domain, as explained at
- * http://creativecommons.org/publicdomain/zero/1.0/
- */
-
-package io.akarin.api.internal.utils.thread;
-import java.util.*;
-import java.util.concurrent.AbstractExecutorService;
-import java.util.concurrent.Callable;
-import java.util.concurrent.CancellationException;
-import java.util.concurrent.ExecutionException;
-import java.util.concurrent.ExecutorCompletionService;
-import java.util.concurrent.ExecutorService;
-import java.util.concurrent.Future;
-import java.util.concurrent.FutureTask;
-import java.util.concurrent.RunnableFuture;
-import java.util.concurrent.TimeUnit;
-import java.util.concurrent.TimeoutException;
-
-/**
- * Provides default implementations of {@link ExecutorService}
- * execution methods. This class implements the {@code submit},
- * {@code invokeAny} and {@code invokeAll} methods using a
- * {@link RunnableFuture} returned by {@code newTaskFor}, which defaults
- * to the {@link FutureTask} class provided in this package.  For example,
- * the implementation of {@code submit(Runnable)} creates an
- * associated {@code RunnableFuture} that is executed and
- * returned. Subclasses may override the {@code newTaskFor} methods
- * to return {@code RunnableFuture} implementations other than
- * {@code FutureTask}.
- *
- * <p><b>Extension example</b>. Here is a sketch of a class
- * that customizes {@link ThreadPoolExecutor} to use
- * a {@code CustomTask} class instead of the default {@code FutureTask}:
- *  <pre> {@code
- * public class CustomThreadPoolExecutor extends ThreadPoolExecutor {
- *
- *   static class CustomTask<V> implements RunnableFuture<V> {...}
- *
- *   protected <V> RunnableFuture<V> newTaskFor(Callable<V> c) {
- *       return new CustomTask<V>(c);
- *   }
- *   protected <V> RunnableFuture<V> newTaskFor(Runnable r, V v) {
- *       return new CustomTask<V>(r, v);
- *   }
- *   // ... add constructors, etc.
- * }}</pre>
- *
- * @since 1.5
- * @author Doug Lea
- */
-public abstract class SuspendableAbstractExecutorService extends AbstractExecutorService implements ExecutorService {
-
-    /**
-     * Returns a {@code RunnableFuture} for the given runnable and default
-     * value.
-     *
-     * @param runnable the runnable task being wrapped
-     * @param value the default value for the returned future
-     * @param <T> the type of the given value
-     * @return a {@code RunnableFuture} which, when run, will run the
-     * underlying runnable and which, as a {@code Future}, will yield
-     * the given value as its result and provide for cancellation of
-     * the underlying task
-     * @since 1.6
-     */
-    protected <T> RunnableFuture<T> newTaskFor(Runnable runnable, T value) {
-        return new FutureTask<T>(runnable, value);
-    }
-
-    /**
-     * Returns a {@code RunnableFuture} for the given callable task.
-     *
-     * @param callable the callable task being wrapped
-     * @param <T> the type of the callable's result
-     * @return a {@code RunnableFuture} which, when run, will call the
-     * underlying callable and which, as a {@code Future}, will yield
-     * the callable's result as its result and provide for
-     * cancellation of the underlying task
-     * @since 1.6
-     */
-    protected <T> RunnableFuture<T> newTaskFor(Callable<T> callable) {
-        return new FutureTask<T>(callable);
-    }
-
-    /**
-     * @throws RejectedExecutionException {@inheritDoc}
-     * @throws NullPointerException       {@inheritDoc}
-     */
-    public Future<?> submit(Runnable task) {
-        if (task == null) throw new NullPointerException();
-        RunnableFuture<Void> ftask = newTaskFor(task, null);
-        execute(ftask);
-        return ftask;
-    }
-
-    /**
-     * @throws RejectedExecutionException {@inheritDoc}
-     * @throws NullPointerException       {@inheritDoc}
-     */
-    public <T> Future<T> submit(Runnable task, T result) {
-        if (task == null) throw new NullPointerException();
-        RunnableFuture<T> ftask = newTaskFor(task, result);
-        execute(ftask);
-        return ftask;
-    }
-
-    /**
-     * @throws RejectedExecutionException {@inheritDoc}
-     * @throws NullPointerException       {@inheritDoc}
-     */
-    public <T> Future<T> submit(Callable<T> task) {
-        if (task == null) throw new NullPointerException();
-        RunnableFuture<T> ftask = newTaskFor(task);
-        execute(ftask);
-        return ftask;
-    }
-
-    /**
-     * the main mechanics of invokeAny.
-     */
-    private <T> T doInvokeAny(Collection<? extends Callable<T>> tasks,
-                              boolean timed, long nanos)
-        throws InterruptedException, ExecutionException, TimeoutException {
-        if (tasks == null)
-            throw new NullPointerException();
-        int ntasks = tasks.size();
-        if (ntasks == 0)
-            throw new IllegalArgumentException();
-        ArrayList<Future<T>> futures = new ArrayList<Future<T>>(ntasks);
-        ExecutorCompletionService<T> ecs =
-            new ExecutorCompletionService<T>(this);
-
-        // For efficiency, especially in executors with limited
-        // parallelism, check to see if previously submitted tasks are
-        // done before submitting more of them. This interleaving
-        // plus the exception mechanics account for messiness of main
-        // loop.
-
-        try {
-            // Record exceptions so that if we fail to obtain any
-            // result, we can throw the last exception we got.
-            ExecutionException ee = null;
-            final long deadline = timed ? System.nanoTime() + nanos : 0L;
-            Iterator<? extends Callable<T>> it = tasks.iterator();
-
-            // Start one task for sure; the rest incrementally
-            futures.add(ecs.submit(it.next()));
-            --ntasks;
-            int active = 1;
-
-            for (;;) {
-                Future<T> f = ecs.poll();
-                if (f == null) {
-                    if (ntasks > 0) {
-                        --ntasks;
-                        futures.add(ecs.submit(it.next()));
-                        ++active;
-                    }
-                    else if (active == 0)
-                        break;
-                    else if (timed) {
-                        f = ecs.poll(nanos, TimeUnit.NANOSECONDS);
-                        if (f == null)
-                            throw new TimeoutException();
-                        nanos = deadline - System.nanoTime();
-                    }
-                    else
-                        f = ecs.take();
-                }
-                if (f != null) {
-                    --active;
-                    try {
-                        return f.get();
-                    } catch (ExecutionException eex) {
-                        ee = eex;
-                    } catch (RuntimeException rex) {
-                        ee = new ExecutionException(rex);
-                    }
-                }
-            }
-
-            if (ee == null)
-                ee = new SuspendableExecutionException();
-            throw ee;
-
-        } finally {
-            for (int i = 0, size = futures.size(); i < size; i++)
-                futures.get(i).cancel(true);
-        }
-    }
-
-    public <T> T invokeAny(Collection<? extends Callable<T>> tasks)
-        throws InterruptedException, ExecutionException {
-        try {
-            return doInvokeAny(tasks, false, 0);
-        } catch (TimeoutException cannotHappen) {
-            assert false;
-            return null;
-        }
-    }
-
-    public <T> T invokeAny(Collection<? extends Callable<T>> tasks,
-                           long timeout, TimeUnit unit)
-        throws InterruptedException, ExecutionException, TimeoutException {
-        return doInvokeAny(tasks, true, unit.toNanos(timeout));
-    }
-
-    public <T> List<Future<T>> invokeAll(Collection<? extends Callable<T>> tasks)
-        throws InterruptedException {
-        if (tasks == null)
-            throw new NullPointerException();
-        ArrayList<Future<T>> futures = new ArrayList<Future<T>>(tasks.size());
-        boolean done = false;
-        try {
-            for (Callable<T> t : tasks) {
-                RunnableFuture<T> f = newTaskFor(t);
-                futures.add(f);
-                execute(f);
-            }
-            for (int i = 0, size = futures.size(); i < size; i++) {
-                Future<T> f = futures.get(i);
-                if (!f.isDone()) {
-                    try {
-                        f.get();
-                    } catch (CancellationException ignore) {
-                    } catch (ExecutionException ignore) {
-                    }
-                }
-            }
-            done = true;
-            return futures;
-        } finally {
-            if (!done)
-                for (int i = 0, size = futures.size(); i < size; i++)
-                    futures.get(i).cancel(true);
-        }
-    }
-
-    public <T> List<Future<T>> invokeAll(Collection<? extends Callable<T>> tasks,
-                                         long timeout, TimeUnit unit)
-        throws InterruptedException {
-        if (tasks == null)
-            throw new NullPointerException();
-        long nanos = unit.toNanos(timeout);
-        ArrayList<Future<T>> futures = new ArrayList<Future<T>>(tasks.size());
-        boolean done = false;
-        try {
-            for (Callable<T> t : tasks)
-                futures.add(newTaskFor(t));
-
-            final long deadline = System.nanoTime() + nanos;
-            final int size = futures.size();
-
-            // Interleave time checks and calls to execute in case
-            // executor doesn't have any/much parallelism.
-            for (int i = 0; i < size; i++) {
-                execute((Runnable)futures.get(i));
-                nanos = deadline - System.nanoTime();
-                if (nanos <= 0L)
-                    return futures;
-            }
-
-            for (int i = 0; i < size; i++) {
-                Future<T> f = futures.get(i);
-                if (!f.isDone()) {
-                    if (nanos <= 0L)
-                        return futures;
-                    try {
-                        f.get(nanos, TimeUnit.NANOSECONDS);
-                    } catch (CancellationException ignore) {
-                    } catch (ExecutionException ignore) {
-                    } catch (TimeoutException toe) {
-                        return futures;
-                    }
-                    nanos = deadline - System.nanoTime();
-                }
-            }
-            done = true;
-            return futures;
-        } finally {
-            if (!done)
-                for (int i = 0, size = futures.size(); i < size; i++)
-                    futures.get(i).cancel(true);
-        }
-    }
-
-}
diff --git a/sources/src/main/java/io/akarin/api/internal/utils/thread/SuspendableExecutionException.java b/sources/src/main/java/io/akarin/api/internal/utils/thread/SuspendableExecutionException.java
deleted file mode 100644
index 896689380..000000000
--- a/sources/src/main/java/io/akarin/api/internal/utils/thread/SuspendableExecutionException.java
+++ /dev/null
@@ -1,51 +0,0 @@
-/*
- * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
- *
- *
- *
- *
- *
- *
- *
- *
- *
- *
- *
- *
- *
- *
- *
- *
- *
- *
- *
- *
- */
-
-/*
- *
- *
- *
- *
- *
- * Written by Doug Lea with assistance from members of JCP JSR-166
- * Expert Group and released to the public domain, as explained at
- * http://creativecommons.org/publicdomain/zero/1.0/
- */
-
-package io.akarin.api.internal.utils.thread;
-
-import java.util.concurrent.ExecutionException;
-
-/**
- * Exception thrown when attempting to retrieve the result of a task
- * that aborted by throwing an exception. This exception can be
- * inspected using the {@link #getCause()} method.
- *
- * @see Future
- * @since 1.5
- * @author Doug Lea
- */
-public class SuspendableExecutionException extends ExecutionException {
-    private static final long serialVersionUID = 7830266012832686185L;
-}
diff --git a/sources/src/main/java/io/akarin/api/internal/utils/thread/SuspendableExecutorCompletionService.java b/sources/src/main/java/io/akarin/api/internal/utils/thread/SuspendableExecutorCompletionService.java
index 4456ed5f1..6204d15c8 100644
--- a/sources/src/main/java/io/akarin/api/internal/utils/thread/SuspendableExecutorCompletionService.java
+++ b/sources/src/main/java/io/akarin/api/internal/utils/thread/SuspendableExecutorCompletionService.java
@@ -38,93 +38,22 @@ package io.akarin.api.internal.utils.thread;
 import java.util.concurrent.BlockingQueue;
 import java.util.concurrent.Callable;
 import java.util.concurrent.CompletionService;
-import java.util.concurrent.Executor;
 import java.util.concurrent.Future;
 import java.util.concurrent.FutureTask;
 import java.util.concurrent.LinkedBlockingQueue;
 import java.util.concurrent.RunnableFuture;
 import java.util.concurrent.TimeUnit;
 
-/**
- * A {@link CompletionService} that uses a supplied {@link Executor}
- * to execute tasks.  This class arranges that submitted tasks are,
- * upon completion, placed on a queue accessible using {@code take}.
- * The class is lightweight enough to be suitable for transient use
- * when processing groups of tasks.
- *
- * <p>
- *
- * <b>Usage Examples.</b>
- *
- * Suppose you have a set of solvers for a certain problem, each
- * returning a value of some type {@code Result}, and would like to
- * run them concurrently, processing the results of each of them that
- * return a non-null value, in some method {@code use(Result r)}. You
- * could write this as:
- *
- * <pre> {@code
- * void solve(Executor e,
- *            Collection<Callable<Result>> solvers)
- *     throws InterruptedException, ExecutionException {
- *     CompletionService<Result> ecs
- *         = new ExecutorCompletionService<Result>(e);
- *     for (Callable<Result> s : solvers)
- *         ecs.submit(s);
- *     int n = solvers.size();
- *     for (int i = 0; i < n; ++i) {
- *         Result r = ecs.take().get();
- *         if (r != null)
- *             use(r);
- *     }
- * }}</pre>
- *
- * Suppose instead that you would like to use the first non-null result
- * of the set of tasks, ignoring any that encounter exceptions,
- * and cancelling all other tasks when the first one is ready:
- *
- * <pre> {@code
- * void solve(Executor e,
- *            Collection<Callable<Result>> solvers)
- *     throws InterruptedException {
- *     CompletionService<Result> ecs
- *         = new ExecutorCompletionService<Result>(e);
- *     int n = solvers.size();
- *     List<Future<Result>> futures
- *         = new ArrayList<Future<Result>>(n);
- *     Result result = null;
- *     try {
- *         for (Callable<Result> s : solvers)
- *             futures.add(ecs.submit(s));
- *         for (int i = 0; i < n; ++i) {
- *             try {
- *                 Result r = ecs.take().get();
- *                 if (r != null) {
- *                     result = r;
- *                     break;
- *                 }
- *             } catch (ExecutionException ignore) {}
- *         }
- *     }
- *     finally {
- *         for (Future<Result> f : futures)
- *             f.cancel(true);
- *     }
- *
- *     if (result != null)
- *         use(result);
- * }}</pre>
- */
 public class SuspendableExecutorCompletionService<V> implements CompletionService<V> {
-    private final Executor executor;
-    private final SuspendableAbstractExecutorService aes;
+    private final SuspendableThreadPoolExecutor executor;
     private final BlockingQueue<Future<V>> completionQueue;
     
-    public static <V> void suspend(SuspendableExecutorCompletionService<V> service) {
-        SuspendableThreadPoolExecutor.suspend((SuspendableThreadPoolExecutor) service.executor);
+    public void suspend() {
+        executor.suspend();
     }
     
-    public static <V> void resume(SuspendableExecutorCompletionService<V> service) {
-        SuspendableThreadPoolExecutor.resume((SuspendableThreadPoolExecutor) service.executor);
+    public void resume() {
+        executor.resume();
     }
 
     /**
@@ -140,17 +69,11 @@ public class SuspendableExecutorCompletionService<V> implements CompletionServic
     }
 
     private RunnableFuture<V> newTaskFor(Callable<V> task) {
-        if (aes == null)
-            return new FutureTask<V>(task);
-        else
-            return aes.newTaskFor(task);
+        return new FutureTask<V>(task);
     }
 
     private RunnableFuture<V> newTaskFor(Runnable task, V result) {
-        if (aes == null)
-            return new FutureTask<V>(task, result);
-        else
-            return aes.newTaskFor(task, result);
+        return new FutureTask<V>(task, result);
     }
 
     /**
@@ -161,12 +84,10 @@ public class SuspendableExecutorCompletionService<V> implements CompletionServic
      * @param executor the executor to use
      * @throws NullPointerException if executor is {@code null}
      */
-    public SuspendableExecutorCompletionService(Executor executor) {
+    public SuspendableExecutorCompletionService(SuspendableThreadPoolExecutor executor) {
         if (executor == null)
             throw new NullPointerException();
         this.executor = executor;
-        this.aes = (executor instanceof SuspendableAbstractExecutorService) ?
-            (SuspendableAbstractExecutorService) executor : null;
         this.completionQueue = new LinkedBlockingQueue<Future<V>>();
     }
 
@@ -183,13 +104,11 @@ public class SuspendableExecutorCompletionService<V> implements CompletionServic
      *        them not to be retrievable.
      * @throws NullPointerException if executor or completionQueue are {@code null}
      */
-    public SuspendableExecutorCompletionService(Executor executor,
+    public SuspendableExecutorCompletionService(SuspendableThreadPoolExecutor executor,
                                      BlockingQueue<Future<V>> completionQueue) {
         if (executor == null || completionQueue == null)
             throw new NullPointerException();
         this.executor = executor;
-        this.aes = (executor instanceof SuspendableAbstractExecutorService) ?
-            (SuspendableAbstractExecutorService) executor : null;
         this.completionQueue = completionQueue;
     }
 
diff --git a/sources/src/main/java/io/akarin/api/internal/utils/thread/SuspendableThreadPoolExecutor.java b/sources/src/main/java/io/akarin/api/internal/utils/thread/SuspendableThreadPoolExecutor.java
index fb1e622a0..317562963 100644
--- a/sources/src/main/java/io/akarin/api/internal/utils/thread/SuspendableThreadPoolExecutor.java
+++ b/sources/src/main/java/io/akarin/api/internal/utils/thread/SuspendableThreadPoolExecutor.java
@@ -34,6 +34,7 @@
  */
 
 package io.akarin.api.internal.utils.thread;
+
 import java.util.concurrent.locks.AbstractQueuedSynchronizer;
 import java.util.concurrent.locks.Condition;
 import java.util.concurrent.locks.ReentrantLock;
@@ -48,282 +49,6 @@ import java.util.concurrent.TimeUnit;
 import java.util.concurrent.atomic.AtomicInteger;
 import java.util.*;
 
-/**
- * An {@link ExecutorService} that executes each submitted task using
- * one of possibly several pooled threads, normally configured
- * using {@link Executors} factory methods.
- *
- * <p>Thread pools address two different problems: they usually
- * provide improved performance when executing large numbers of
- * asynchronous tasks, due to reduced per-task invocation overhead,
- * and they provide a means of bounding and managing the resources,
- * including threads, consumed when executing a collection of tasks.
- * Each {@code ThreadPoolExecutor} also maintains some basic
- * statistics, such as the number of completed tasks.
- *
- * <p>To be useful across a wide range of contexts, this class
- * provides many adjustable parameters and extensibility
- * hooks. However, programmers are urged to use the more convenient
- * {@link Executors} factory methods {@link
- * Executors#newCachedThreadPool} (unbounded thread pool, with
- * automatic thread reclamation), {@link Executors#newFixedThreadPool}
- * (fixed size thread pool) and {@link
- * Executors#newSingleThreadExecutor} (single background thread), that
- * preconfigure settings for the most common usage
- * scenarios. Otherwise, use the following guide when manually
- * configuring and tuning this class:
- *
- * <dl>
- *
- * <dt>Core and maximum pool sizes</dt>
- *
- * <dd>A {@code ThreadPoolExecutor} will automatically adjust the
- * pool size (see {@link #getPoolSize})
- * according to the bounds set by
- * corePoolSize (see {@link #getCorePoolSize}) and
- * maximumPoolSize (see {@link #getMaximumPoolSize}).
- *
- * When a new task is submitted in method {@link #execute(Runnable)},
- * and fewer than corePoolSize threads are running, a new thread is
- * created to handle the request, even if other worker threads are
- * idle.  If there are more than corePoolSize but less than
- * maximumPoolSize threads running, a new thread will be created only
- * if the queue is full.  By setting corePoolSize and maximumPoolSize
- * the same, you create a fixed-size thread pool. By setting
- * maximumPoolSize to an essentially unbounded value such as {@code
- * Integer.MAX_VALUE}, you allow the pool to accommodate an arbitrary
- * number of concurrent tasks. Most typically, core and maximum pool
- * sizes are set only upon construction, but they may also be changed
- * dynamically using {@link #setCorePoolSize} and {@link
- * #setMaximumPoolSize}. </dd>
- *
- * <dt>On-demand construction</dt>
- *
- * <dd>By default, even core threads are initially created and
- * started only when new tasks arrive, but this can be overridden
- * dynamically using method {@link #prestartCoreThread} or {@link
- * #prestartAllCoreThreads}.  You probably want to prestart threads if
- * you construct the pool with a non-empty queue. </dd>
- *
- * <dt>Creating new threads</dt>
- *
- * <dd>New threads are created using a {@link ThreadFactory}.  If not
- * otherwise specified, a {@link Executors#defaultThreadFactory} is
- * used, that creates threads to all be in the same {@link
- * ThreadGroup} and with the same {@code NORM_PRIORITY} priority and
- * non-daemon status. By supplying a different ThreadFactory, you can
- * alter the thread's name, thread group, priority, daemon status,
- * etc. If a {@code ThreadFactory} fails to create a thread when asked
- * by returning null from {@code newThread}, the executor will
- * continue, but might not be able to execute any tasks. Threads
- * should possess the "modifyThread" {@code RuntimePermission}. If
- * worker threads or other threads using the pool do not possess this
- * permission, service may be degraded: configuration changes may not
- * take effect in a timely manner, and a shutdown pool may remain in a
- * state in which termination is possible but not completed.</dd>
- *
- * <dt>Keep-alive times</dt>
- *
- * <dd>If the pool currently has more than corePoolSize threads,
- * excess threads will be terminated if they have been idle for more
- * than the keepAliveTime (see {@link #getKeepAliveTime(TimeUnit)}).
- * This provides a means of reducing resource consumption when the
- * pool is not being actively used. If the pool becomes more active
- * later, new threads will be constructed. This parameter can also be
- * changed dynamically using method {@link #setKeepAliveTime(long,
- * TimeUnit)}.  Using a value of {@code Long.MAX_VALUE} {@link
- * TimeUnit#NANOSECONDS} effectively disables idle threads from ever
- * terminating prior to shut down. By default, the keep-alive policy
- * applies only when there are more than corePoolSize threads. But
- * method {@link #allowCoreThreadTimeOut(boolean)} can be used to
- * apply this time-out policy to core threads as well, so long as the
- * keepAliveTime value is non-zero. </dd>
- *
- * <dt>Queuing</dt>
- *
- * <dd>Any {@link BlockingQueue} may be used to transfer and hold
- * submitted tasks.  The use of this queue interacts with pool sizing:
- *
- * <ul>
- *
- * <li> If fewer than corePoolSize threads are running, the Executor
- * always prefers adding a new thread
- * rather than queuing.</li>
- *
- * <li> If corePoolSize or more threads are running, the Executor
- * always prefers queuing a request rather than adding a new
- * thread.</li>
- *
- * <li> If a request cannot be queued, a new thread is created unless
- * this would exceed maximumPoolSize, in which case, the task will be
- * rejected.</li>
- *
- * </ul>
- *
- * There are three general strategies for queuing:
- * <ol>
- *
- * <li> <em> Direct handoffs.</em> A good default choice for a work
- * queue is a {@link SynchronousQueue} that hands off tasks to threads
- * without otherwise holding them. Here, an attempt to queue a task
- * will fail if no threads are immediately available to run it, so a
- * new thread will be constructed. This policy avoids lockups when
- * handling sets of requests that might have internal dependencies.
- * Direct handoffs generally require unbounded maximumPoolSizes to
- * avoid rejection of new submitted tasks. This in turn admits the
- * possibility of unbounded thread growth when commands continue to
- * arrive on average faster than they can be processed.  </li>
- *
- * <li><em> Unbounded queues.</em> Using an unbounded queue (for
- * example a {@link LinkedBlockingQueue} without a predefined
- * capacity) will cause new tasks to wait in the queue when all
- * corePoolSize threads are busy. Thus, no more than corePoolSize
- * threads will ever be created. (And the value of the maximumPoolSize
- * therefore doesn't have any effect.)  This may be appropriate when
- * each task is completely independent of others, so tasks cannot
- * affect each others execution; for example, in a web page server.
- * While this style of queuing can be useful in smoothing out
- * transient bursts of requests, it admits the possibility of
- * unbounded work queue growth when commands continue to arrive on
- * average faster than they can be processed.  </li>
- *
- * <li><em>Bounded queues.</em> A bounded queue (for example, an
- * {@link ArrayBlockingQueue}) helps prevent resource exhaustion when
- * used with finite maximumPoolSizes, but can be more difficult to
- * tune and control.  Queue sizes and maximum pool sizes may be traded
- * off for each other: Using large queues and small pools minimizes
- * CPU usage, OS resources, and context-switching overhead, but can
- * lead to artificially low throughput.  If tasks frequently block (for
- * example if they are I/O bound), a system may be able to schedule
- * time for more threads than you otherwise allow. Use of small queues
- * generally requires larger pool sizes, which keeps CPUs busier but
- * may encounter unacceptable scheduling overhead, which also
- * decreases throughput.  </li>
- *
- * </ol>
- *
- * </dd>
- *
- * <dt>Rejected tasks</dt>
- *
- * <dd>New tasks submitted in method {@link #execute(Runnable)} will be
- * <em>rejected</em> when the Executor has been shut down, and also when
- * the Executor uses finite bounds for both maximum threads and work queue
- * capacity, and is saturated.  In either case, the {@code execute} method
- * invokes the {@link
- * RejectedExecutionHandler#rejectedExecution(Runnable, ThreadPoolExecutor)}
- * method of its {@link RejectedExecutionHandler}.  Four predefined handler
- * policies are provided:
- *
- * <ol>
- *
- * <li> In the default {@link SuspendableThreadPoolExecutor.AbortPolicy}, the
- * handler throws a runtime {@link RejectedExecutionException} upon
- * rejection. </li>
- *
- * <li> In {@link SuspendableThreadPoolExecutor.CallerRunsPolicy}, the thread
- * that invokes {@code execute} itself runs the task. This provides a
- * simple feedback control mechanism that will slow down the rate that
- * new tasks are submitted. </li>
- *
- * <li> In {@link SuspendableThreadPoolExecutor.DiscardPolicy}, a task that
- * cannot be executed is simply dropped.  </li>
- *
- * <li>In {@link SuspendableThreadPoolExecutor.DiscardOldestPolicy}, if the
- * executor is not shut down, the task at the head of the work queue
- * is dropped, and then execution is retried (which can fail again,
- * causing this to be repeated.) </li>
- *
- * </ol>
- *
- * It is possible to define and use other kinds of {@link
- * RejectedExecutionHandler} classes. Doing so requires some care
- * especially when policies are designed to work only under particular
- * capacity or queuing policies. </dd>
- *
- * <dt>Hook methods</dt>
- *
- * <dd>This class provides {@code protected} overridable
- * {@link #beforeExecute(Thread, Runnable)} and
- * {@link #afterExecute(Runnable, Throwable)} methods that are called
- * before and after execution of each task.  These can be used to
- * manipulate the execution environment; for example, reinitializing
- * ThreadLocals, gathering statistics, or adding log entries.
- * Additionally, method {@link #terminated} can be overridden to perform
- * any special processing that needs to be done once the Executor has
- * fully terminated.
- *
- * <p>If hook or callback methods throw exceptions, internal worker
- * threads may in turn fail and abruptly terminate.</dd>
- *
- * <dt>Queue maintenance</dt>
- *
- * <dd>Method {@link #getQueue()} allows access to the work queue
- * for purposes of monitoring and debugging.  Use of this method for
- * any other purpose is strongly discouraged.  Two supplied methods,
- * {@link #remove(Runnable)} and {@link #purge} are available to
- * assist in storage reclamation when large numbers of queued tasks
- * become cancelled.</dd>
- *
- * <dt>Finalization</dt>
- *
- * <dd>A pool that is no longer referenced in a program <em>AND</em>
- * has no remaining threads will be {@code shutdown} automatically. If
- * you would like to ensure that unreferenced pools are reclaimed even
- * if users forget to call {@link #shutdown}, then you must arrange
- * that unused threads eventually die, by setting appropriate
- * keep-alive times, using a lower bound of zero core threads and/or
- * setting {@link #allowCoreThreadTimeOut(boolean)}.  </dd>
- *
- * </dl>
- *
- * <p><b>Extension example</b>. Most extensions of this class
- * override one or more of the protected hook methods. For example,
- * here is a subclass that adds a simple pause/resume feature:
- *
- *  <pre> {@code
- * class PausableThreadPoolExecutor extends ThreadPoolExecutor {
- *   private boolean isPaused;
- *   private ReentrantLock pauseLock = new ReentrantLock();
- *   private Condition unpaused = pauseLock.newCondition();
- *
- *   public PausableThreadPoolExecutor(...) { super(...); }
- *
- *   protected void beforeExecute(Thread t, Runnable r) {
- *     super.beforeExecute(t, r);
- *     pauseLock.lock();
- *     try {
- *       while (isPaused) unpaused.await();
- *     } catch (InterruptedException ie) {
- *       t.interrupt();
- *     } finally {
- *       pauseLock.unlock();
- *     }
- *   }
- *
- *   public void pause() {
- *     pauseLock.lock();
- *     try {
- *       isPaused = true;
- *     } finally {
- *       pauseLock.unlock();
- *     }
- *   }
- *
- *   public void resume() {
- *     pauseLock.lock();
- *     try {
- *       isPaused = false;
- *       unpaused.signalAll();
- *     } finally {
- *       pauseLock.unlock();
- *     }
- *   }
- * }}</pre>
- *
- * @since 1.5
- * @author Doug Lea
- */
 public class SuspendableThreadPoolExecutor extends ThreadPoolExecutor {
     /**
      * The main pool control state, ctl, is an atomic integer packing
@@ -398,16 +123,14 @@ public class SuspendableThreadPoolExecutor extends ThreadPoolExecutor {
     private static int workerCountOf(int c)  { return c & CAPACITY; }
     private static int ctlOf(int rs, int wc) { return rs | wc; }
     
-    @SuppressWarnings("deprecation")
-    public static void suspend(SuspendableThreadPoolExecutor executor) {
-        long currentThread = Thread.currentThread().getId();
-        for (Worker worker : executor.workers) if (worker.thread.getId() != currentThread) worker.thread.suspend();
+    public void suspend() {
+        Thread curThread = Thread.currentThread();
+        for (Worker worker : workers) if (worker.thread != curThread) worker.thread.suspend();
     }
     
-    @SuppressWarnings("deprecation")
-    public static void resume(SuspendableThreadPoolExecutor executor) {
-        long currentThread = Thread.currentThread().getId();
-        for (Worker worker : executor.workers) if (worker.thread.getId() != currentThread) worker.thread.resume();
+    public void resume() {
+        Thread curThread = Thread.currentThread();
+        for (Worker worker : workers) if (worker.thread != curThread) worker.thread.resume();
     }
 
     /*
diff --git a/sources/src/main/java/io/akarin/server/mixin/core/MixinTimingHandler.java b/sources/src/main/java/io/akarin/server/mixin/core/MixinTimingHandler.java
index 1ae72ae72..220295249 100644
--- a/sources/src/main/java/io/akarin/server/mixin/core/MixinTimingHandler.java
+++ b/sources/src/main/java/io/akarin/server/mixin/core/MixinTimingHandler.java
@@ -18,8 +18,8 @@ import net.minecraft.server.MinecraftServer;
 public abstract class MixinTimingHandler implements IMixinTimingHandler {
     @Shadow @Final String name;
     @Shadow private boolean enabled;
-    @Shadow private volatile long start;
-    @Shadow private volatile int timingDepth;
+    @Shadow private long start;
+    @Shadow private int timingDepth;
     
     @Shadow abstract void addDiff(long diff);
     @Shadow public abstract Timing startTiming();
@@ -47,7 +47,7 @@ public abstract class MixinTimingHandler implements IMixinTimingHandler {
         if (!alreadySync) {
             Thread curThread = Thread.currentThread();
             if (curThread != MinecraftServer.getServer().primaryThread) {
-                if (false && !AkarinGlobalConfig.silentAsyncTimings) {
+                if (!AkarinGlobalConfig.silentAsyncTimings) {
                     Bukkit.getLogger().log(Level.SEVERE, "stopTiming called async for " + name);
                     Thread.dumpStack();
                 }
diff --git a/sources/src/main/java/org/bukkit/plugin/EventExecutor.java b/sources/src/main/java/org/bukkit/plugin/EventExecutor.java
index c8476a85b..2adef1bb7 100644
--- a/sources/src/main/java/org/bukkit/plugin/EventExecutor.java
+++ b/sources/src/main/java/org/bukkit/plugin/EventExecutor.java
@@ -3,8 +3,6 @@ package org.bukkit.plugin;
 import org.bukkit.event.Event;
 import org.bukkit.event.EventException;
 import org.bukkit.event.Listener;
-import org.bukkit.event.block.BlockPhysicsEvent;
-
 // Paper start
 import java.lang.reflect.Method;
 import java.lang.reflect.Modifier;
@@ -22,6 +20,10 @@ import io.akarin.api.internal.Akari;
 import io.akarin.api.internal.utils.thread.SuspendableExecutorCompletionService;
 // Paper end
 
+/**
+ * Akarin Changes Note
+ * 1) Suspend for event (safety issue)
+ */
 /**
  * Interface which defines the class for event call backs to plugins
  */
@@ -71,11 +73,11 @@ public interface EventExecutor {
                         if (!eventClass.isInstance(event)) return;
                         try {
                             Akari.eventSuspendTiming.startTimingIfSync(); // Akarin
-                            SuspendableExecutorCompletionService.suspend(Akari.STAGE_TICK); // Akarin
+                            Akari.STAGE_TICK.suspend(); // Akarin
                             Akari.eventSuspendTiming.stopTimingIfSync(); // Akarin
                             asmExecutor.execute(listener, event);
                             Akari.eventResumeTiming.startTimingIfSync(); // Akarin
-                            SuspendableExecutorCompletionService.resume(Akari.STAGE_TICK); // Akarin
+                            Akari.STAGE_TICK.resume(); // Akarin
                             Akari.eventResumeTiming.stopTimingIfSync(); // Akarin
                         } catch (Exception e) {
                             throw new EventException(e);