public bool Remove(T item)
 {
     using (var locker = new AutoReaderWriterLockSlim(_lock, LockMode.Write))
     {
         return(_hashSet.Remove(item));
     }
 }
 public void Clear()
 {
     using (var locker = new AutoReaderWriterLockSlim(_lock, LockMode.Write))
     {
         _hashSet.Clear();
     }
 }