Py4JJava在单机上测试Jupyter笔记本中的Pyspark时出错

Question

我是Spark的新手，最近用自制软件在mac上安装了它(系统中有Python 2.7(

brew install apache-spark

然后在我安装了python 3.6的虚拟环境中使用pip3安装了Pyspark。

/Users/xxx/venv/bin/python /Users/xxx/venv/bin/pip3 install pyspark

当我在Jupyter笔记本中运行下面的代码来测试Spark是否在一台机器上运行时：

from pyspark.context import SparkContext
sc = SparkContext.getOrCreate()
import random
num_samples = 100000000
def inside(p):     
x, y = random.random(), random.random()
return x*x + y*y < 1
count = sc.parallelize(range(0, num_samples)).filter(inside).count()
pi = 4 * count / num_samples
print(pi)
sc.stop()

我在sc.parallelize中遇到以下错误：

Py4JJavaError                             Traceback (most recent call last)
<ipython-input-3-482026ac7386> in <module>
8     return x*x + y*y < 1
9 
---> 10 count = sc.parallelize(range(0, num_samples)).filter(inside).count()
11 
12 pi = 4 * count / num_samples
~/venv/deep_learning/lib/python3.6/site-packages/pyspark/rdd.py in count(self)
1139         3
1140         """
-> 1141         return self.mapPartitions(lambda i: [sum(1 for _ in i)]).sum()
1142 
1143     def stats(self):
~/venv/deep_learning/lib/python3.6/site-packages/pyspark/rdd.py in sum(self)
1130         6.0
1131         """
-> 1132         return self.mapPartitions(lambda x: [sum(x)]).fold(0, operator.add)
1133 
1134     def count(self):
~/venv/deep_learning/lib/python3.6/site-packages/pyspark/rdd.py in fold(self, zeroValue, op)
1001         # zeroValue provided to each partition is unique from the one provided
1002         # to the final reduce call
-> 1003         vals = self.mapPartitions(func).collect()
1004         return reduce(op, vals, zeroValue)
1005 
~/venv/deep_learning/lib/python3.6/site-packages/pyspark/rdd.py in collect(self)
887         
888         with SCCallSiteSync(self.context) as css:
-> 889             sock_info = self.ctx._jvm.PythonRDD.collectAndServe(self._jrdd.rdd())
890         return list(_load_from_socket(sock_info, self._jrdd_deserializer))
891 
~/venv/deep_learning/lib/python3.6/site-packages/py4j/java_gateway.py in __call__(self, *args)
1303         answer = self.gateway_client.send_command(command)
1304         return_value = get_return_value(
-> 1305             answer, self.gateway_client, self.target_id, self.name)
1306 
1307         for temp_arg in temp_args:
~/venv/deep_learning/lib/python3.6/site-packages/py4j/protocol.py in get_return_value(answer, gateway_client, target_id, name)
326                 raise Py4JJavaError(
327                     "An error occurred while calling {0}{1}{2}.n".
-> 328                     format(target_id, ".", name), value)
329             else:
330                 raise Py4JError(
Py4JJavaError: An error occurred while calling z:org.apache.spark.api.python.PythonRDD.collectAndServe.
: org.apache.spark.SparkException: Job aborted due to stage failure: Task 2 in stage 0.0 failed 1 times, most recent failure: Lost task 2.0 in stage 0.0 (TID 2, 192.168.0.15, executor driver): org.apache.spark.api.python.PythonException: Traceback (most recent call last):
File "/Users/xxx/venv/deep_learning/lib/python3.6/site-packages/pyspark/python/lib/pyspark.zip/pyspark/worker.py", line 477, in main
("%d.%d" % sys.version_info[:2], version))
Exception: Python in worker has different version 2.7 than that in driver 3.6, PySpark cannot run with different minor versions. Please check environment variables PYSPARK_PYTHON and PYSPARK_DRIVER_PYTHON are correctly set.

我在/.bash_profile:中配置了Pyspark路径，如下所示

export SPARK_HOME=/usr/local/Cellar/apache-spark/3.0.1/libexec
export PYTHONPATH=/usr/local/Cellar/apache-spark/3.0.1/libexec/python/:$PYTHONP$
export PYSPARK_PYTHON=/Users/xxx/venv/bin/python
export PYSPARK_DRIVER_PYTHON=/Users/xxx/venv/bin/python

有人知道我在这里做错了什么吗？如有任何建议，我们将不胜感激。

Answer 1

这个问题似乎特别与Pyspark有关。这个问题可以通过使用findspark软件包来解决。以下是findspark自述文件中的引用：

PySpark默认不在sys.path上，但这并不意味着它不能用作常规库。您可以通过将pyspark符号链接到您的站点包中，或者在运行时将pyspark添加到sys.path中来解决此问题。findspark做后者。

在启动SparkContext之前添加以下代码可以解决问题：

import findspark
findspark.init()