Jupyter内核Apache toree启动超时

Question

我在Ubuntu 16.04系统中安装了以下命令：

$ pip install --pre toree

$ jupyter toree install --interpreters=Scala,PySpark,SQL 

然后我检查了内核列表。我成功地安装了内核：

$ jupyter kernelspec list

Available kernels:
  python3                 /home/ypdx/programs/anaconda3/lib/python3.5/site-packages/ipykernel/resources
  apache_toree_pyspark    /usr/local/share/jupyter/kernels/apache_toree_pyspark
  apache_toree_scala      /usr/local/share/jupyter/kernels/apache_toree_scala
  apache_toree_sql        /usr/local/share/jupyter/kernels/apache_toree_sql

然后我启动jupyter，问题就在于：当我使用该内核创建一个新笔记本时，apache_toree_scala和apache_toree_pyspark内核都将运行错误“timeout”。以下是错误消息：

Timeout waiting for kernel_info reply from d98705f0-4bba-4c69-af7f-da99379219f5

我的ubuntu安装在VirtualBox中。但我认为这应该不是问题。