Spark notes

Spark References

Videos

• GU ANLY 502, 2017 (From the course I taught at Georgetown)

Books

• Learning Spark
• Spark: The Definitive Guide
• High Performance Spark
• Python for Data Analysis: Data Wrangling with Pandas, NumPy, and IPython

Spark Ideas

Spark on MacOS

You can run Spark locally on a Mac without having a cluster. Spark will use all of your available CPUs.

Use this:

1. Install anaconda
2. conda install pyspark

File Management

Adding files to the nodes:

   sc.addFile(filename)

• https://medium.com/@rbahaguejr/adding-python-files-to-pyspark-job-b725e02c8ab2
• https://medium.com/@rbahaguejr/adding-python-files-to-pyspark-job-b725e02c8ab2

Tuning

• https://stackoverflow.com/questions/37871194/how-to-tune-spark-executor-number-cores-and-executor-memory
• https://blog.cloudera.com/blog/2015/03/how-to-tune-your-apache-spark-jobs-part-2/
• http://site.clairvoyantsoft.com/understanding-resource-allocation-configurations-spark-application/

Spark Practce

• https://developerzen.com/best-practices-writing-production-grade-pyspark-jobs-cb688ac4d20f (most about packaging and a shared context)

Demos

Find the nodes where you are running, entirely from within Spark (using EMR). Below was run on a 2-node cluster.

$ sudo pip-3.4 install ipython
$ cat func.py
def myfun(a):
    import socket,os
    return socket.gethostname()+"-"+str(os.getpid())

[hadoop@ip-10-239-83-234 ~]$ PYSPARK_DRIVER_PYTHON=ipython3 PYSPARK_PYTHON=python34 pyspark --py-files func.py
Python 3.4.3 (default, Sep  1 2016, 23:33:38)
Type 'copyright', 'credits' or 'license' for more information
IPython 6.2.0 -- An enhanced Interactive Python. Type '?' for help.
Setting default log level to "WARN".
To adjust logging level use sc.setLogLevel(newLevel). For SparkR, use setLogLevel(newLevel).
17/09/21 18:11:49 WARN Client: Neither spark.yarn.jars nor spark.yarn.archive is set, falling back to uploading libraries under SPARK_HOME.
17/09/21 18:12:05 WARN CredentialsLegacyConfigLocationProvider: Found the legacy config profiles file at [/home/hadoop/.aws/config]. Please move it to the latest default location [~/.aws/credentials].
Welcome to
      ____              __
     / __/__  ___ _____/ /__
    _\ \/ _ \/ _ `/ __/  '_/
   /__ / .__/\_,_/_/ /_/\_\   version 2.2.0
      /_/

Using Python version 3.4.3 (default, Sep  1 2016 23:33:38)
SparkSession available as 'spark'.

In [1]: from func import myfun

In [2]: myfun(10)
Out[2]: 'ip-10-239-83-234-24121'

In [5]: a = sc.parallelize(range(1,10)).map(lambda num:myfun(num))

In [6]: a.take(10)
Out[6]:
['ip-10-144-32-86-32083',
 'ip-10-144-32-86-32083',
 'ip-10-144-32-86-32091',
 'ip-10-144-32-86-32091',
 'ip-10-144-32-86-32088',
 'ip-10-144-32-86-32088',
 'ip-10-144-32-86-32094',
 'ip-10-144-32-86-32094',
 'ip-10-144-32-86-32094']

In [10]: sc.parallelize(range(1,10)).map(lambda num:(myfun(num),1)).reduceByKey(lambda a,b:a+b).collect()
Out[10]:
[('ip-10-144-32-86-32274', 3),
 ('ip-10-144-32-86-32271', 2),
 ('ip-10-144-32-86-32264', 2),
 ('ip-10-144-32-86-32267', 2)]

In [11]: sc.parallelize(range(1,1000)).map(lambda num:(myfun(num),1)).reduceByKey(lambda a,b:a+b).collect()
Out[11]:
[('ip-10-144-32-86-32287', 249),
 ('ip-10-144-32-86-32290', 250),
 ('ip-10-144-32-86-32296', 250),
 ('ip-10-144-32-86-32284', 250)]

In [12]: sc.parallelize(range(1,1000*1000)).map(lambda num:(myfun(num),1)).reduceByKey(lambda a,b:a+b).collect()
Out[12]:
[('ip-10-144-32-86-32323', 249999),
 ('ip-10-144-32-86-32330', 250000),
 ('ip-10-144-32-86-32320', 250000),
 ('ip-10-144-32-86-32326', 250000)]