After `VDataStreamRecvr::SenderQueue::close` clears `_block_queue`, calling `VDataStreamRecvr::SenderQueue::add_block` again will cause a memory leak. So, change the lock position, like the other add_block and add_batch.
After `VDataStreamRecvr::SenderQueue::close` clears `_block_queue`, calling `VDataStreamRecvr::SenderQueue::add_block` again will cause a memory leak. So, change the lock position, like the other add_block and add_batch.