apache spark "Py4JError: Answer from Java side is empty" - apache-spark

Question

I get this error every time...
I use sparkling water...
My conf-file:
***"spark.driver.memory 65g
spark.python.worker.memory 65g
spark.master local[*]"***
The amount of data is about 5 Gb.
There is no another information about this error...
Does anybody know why it happens? Thank you!
***"ERROR:py4j.java_gateway:Error while sending or receiving.
Traceback (most recent call last):
File "/data/analytics/Spark1.6.1/python/lib/py4j-0.9-src.zip/py4j/java_gateway.py", line 746, in send_command
raise Py4JError("Answer from Java side is empty")
Py4JError: Answer from Java side is empty
ERROR:py4j.java_gateway:An error occurred while trying to connect to the Java server
Traceback (most recent call last):
File "/data/analytics/Spark1.6.1/python/lib/py4j-0.9-src.zip/py4j/java_gateway.py", line 690, in start
self.socket.connect((self.address, self.port))
File "/usr/local/anaconda/lib/python2.7/socket.py", line 228, in meth
return getattr(self._sock,name)(*args)
error: [Errno 111] Connection refused
ERROR:py4j.java_gateway:An error occurred while trying to connect to the Java server
Traceback (most recent call last):
File "/data/analytics/Spark1.6.1/python/lib/py4j-0.9-src.zip/py4j/java_gateway.py", line 690, in start
self.socket.connect((self.address, self.port))
File "/usr/local/anaconda/lib/python2.7/socket.py", line 228, in meth
return getattr(self._sock,name)(*args)
error: [Errno 111] Connection refused
ERROR:py4j.java_gateway:An error occurred while trying to connect to the Java server
Traceback (most recent call last):
File "/data/analytics/Spark1.6.1/python/lib/py4j-0.9-src.zip/py4j/java_gateway.py", line 690, in start
self.socket.connect((self.address, self.port))
File "/usr/local/anaconda/lib/python2.7/socket.py", line 228, in meth
return getattr(self._sock,name)(*args)
error: [Errno 111] Connection refused"***

Answer 1

Have you tried setting spark.executor.memory and spark.driver.memory in your Spark configuration file?
See https://stackoverflow.com/a/22742982/5453184 for more info.

Answer 2

Usually, you'll see this error when the Java process get silently killed by the OOM Killer.
The OOM Killer (Out of Memory Killer) is a Linux process that kicks in when the system becomes critically low on memory. It selects a process based on its "badness" score and kills it to reclaim memory.
Read more on OOM Killer here.
Increasing spark.executor.memory and/or spark.driver.memory values will only make things worse in this case, i.e. you may want to do the opposite!
Other options would be to:
increase the number of partitions if you're working with very big data sources;
increase the number of worker nodes;
add more physical memory to worker/driver nodes;
Or, if you're running your driver/workers using docker:
increase docker memory limit;
set --oom-kill-disable on your containers, but make sure you understand possible consequences!
Read more on --oom-kill-disable and other docker memory settings here.

Answer 3

Another point to note if you are on wsl2 using pyspark. Ensure that your wsl2 config file has an increased memory.
# Settings apply across all Linux distros running on WSL 2
[wsl2]
# Limits VM memory to use no more than 4 GB, this can be set as whole numbers using GB or MB
memory=12GB # This was originally set to 3gb which caused me to fail since spark.executor.memory and spark.driver.memory was only able to MAX of 3gb regardless of how high i set it.
# Sets the VM to use eight virtual processors
processors=8
for reference. your .wslconfig config file should be located in C:\Users\USERNAME