### What changes were proposed in this pull request?
`spark.buffer.size` not applied in driver from pyspark. In this PR I've fixed this issue.
### Why are the changes needed?
Apply the mentioned config on driver side.
### Does this PR introduce _any_ user-facing change?
No.
### How was this patch tested?
Existing unit tests + manually.
Added the following code temporarily:
```
def local_connect_and_auth(port, auth_secret):
...
sock.connect(sa)
print("SPARK_BUFFER_SIZE: %d" % int(os.environ.get("SPARK_BUFFER_SIZE", 65536))) <- This is the addition
sockfile = sock.makefile("rwb", int(os.environ.get("SPARK_BUFFER_SIZE", 65536)))
...
```
Test:
```
#Compile Spark
echo "spark.buffer.size 10000" >> conf/spark-defaults.conf
$ ./bin/pyspark
Python 3.8.5 (default, Jul 21 2020, 10:48:26)
[Clang 11.0.3 (clang-1103.0.32.62)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
20/12/03 13:38:13 WARN NativeCodeLoader: Unable to load native-hadoop library for your platform... using builtin-java classes where applicable
Setting default log level to "WARN".
To adjust logging level use sc.setLogLevel(newLevel). For SparkR, use setLogLevel(newLevel).
20/12/03 13:38:14 WARN SparkEnv: I/O encryption enabled without RPC encryption: keys will be visible on the wire.
Welcome to
____ __
/ __/__ ___ _____/ /__
_\ \/ _ \/ _ `/ __/ '_/
/__ / .__/\_,_/_/ /_/\_\ version 3.1.0-SNAPSHOT
/_/
Using Python version 3.8.5 (default, Jul 21 2020 10:48:26)
Spark context Web UI available at http://192.168.0.189:4040
Spark context available as 'sc' (master = local[*], app id = local-1606999094506).
SparkSession available as 'spark'.
>>> sc.setLogLevel("TRACE")
>>> sc.parallelize([0, 2, 3, 4, 6], 5).glom().collect()
...
SPARK_BUFFER_SIZE: 10000
...
[[0], [2], [3], [4], [6]]
>>>
```
Closes#30592 from gaborgsomogyi/SPARK-33629.
Authored-by: Gabor Somogyi <gabor.g.somogyi@gmail.com>
Signed-off-by: HyukjinKwon <gurwls223@apache.org>
bd711863fd