How to reduce the verbosity of Spark's runtime output?

Question

How to reduce the amount of trace info the Spark runtime produces?

The default is too verbose,

How to turn off it, and turn on it when I need.

Verbose mode
scala> val la = sc.parallelize(List(12,4,5,3,4,4,6,781))
scala> la.collect
15/01/28 09:57:24 INFO SparkContext: Starting job: collect at <console>:15
15/01/28 09:57:24 INFO DAGScheduler: Got job 3 (collect at <console>:15) with 1 output
...
15/01/28 09:57:24 INFO Executor: Running task 0.0 in stage 3.0 (TID 3)
15/01/28 09:57:24 INFO Executor: Finished task 0.0 in stage 3.0 (TID 3). 626 bytes result sent to driver
15/01/28 09:57:24 INFO DAGScheduler: Stage 3 (collect at <console>:15) finished in 0.002 s
15/01/28 09:57:24 INFO DAGScheduler: Job 3 finished: collect at <console>:15, took 0.020061 s
res5: Array[Int] = Array(12, 4, 5, 3, 4, 4, 6, 781)

Silent mode(expected)
scala> val la = sc.parallelize(List(12,4,5,3,4,4,6,781))
scala> la.collect
res5: Array[Int] = Array(12, 4, 5, 3, 4, 4, 6, 781) 

Answer 1

You may find the logging statements that get printed in the shell distracting. You can control the verbosity of the logging. To do this, you can create a file in the conf directory called log4j.properties. The Spark developers already include a template for this file called log4j.properties.template. To make the logging less verbose, make a copy of conf/log4j.properties.template called conf/log4j.properties and find the following line:

log4j.rootCategory=INFO, console

Then lower the log level so that we only show WARN message and above by changing it to the following:

log4j.rootCategory=WARN, console

When you re-open the shell, you should see less output.