PoolImpl.java

@Override
protected void onCreate(@Nullable Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    mCachedThreadPool.openNewPool(this);

}

@Override
protected void onDestroy() {
    super.onDestroy();
    mCachedThreadPool.closePool(this);
}

public CachedThreadPool getCachedThreadPool() {
    return mCachedThreadPool;
}

...
getCachedThreadPool().executeTask(task, MainActivity.this);