[SPARK-3634] [PySpark] User's module should take precedence over system modules

Python modules added through addPyFile should take precedence over system modules.

This patch put the path for user added module in the front of sys.path (just after '').

Author: Davies Liu <davies.liu@gmail.com>

Closes #2492 from davies/path and squashes the following commits:

4a2af78 [Davies Liu] fix tests
f7ff4da [Davies Liu] ad license header
6b0002f [Davies Liu] add tests
c16c392 [Davies Liu] put addPyFile in front of sys.path

1 files changed, 5 insertions, 6 deletions

diff --git a/python/pyspark/context.py b/python/pyspark/context.py
index 064a24bff5..8e7b00469e 100644
--- a/python/pyspark/context.py
+++ b/python/pyspark/context.py
@@ -171,7 +171,7 @@ class SparkContext(object):
 
         SparkFiles._sc = self
         root_dir = SparkFiles.getRootDirectory()
-        sys.path.append(root_dir)
+        sys.path.insert(1, root_dir)
 
         # Deploy any code dependencies specified in the constructor
         self._python_includes = list()
@@ -183,10 +183,9 @@ class SparkContext(object):
         for path in self._conf.get("spark.submit.pyFiles", "").split(","):
             if path != "":
                 (dirname, filename) = os.path.split(path)
-                self._python_includes.append(filename)
-                sys.path.append(path)
-                if dirname not in sys.path:
-                    sys.path.append(dirname)
+                if filename.lower().endswith("zip") or filename.lower().endswith("egg"):
+                    self._python_includes.append(filename)
+                    sys.path.insert(1, os.path.join(SparkFiles.getRootDirectory(), filename))
 
         # Create a temporary directory inside spark.local.dir:
         local_dir = self._jvm.org.apache.spark.util.Utils.getLocalDir(self._jsc.sc().conf())
@@ -667,7 +666,7 @@ class SparkContext(object):
         if filename.endswith('.zip') or filename.endswith('.ZIP') or filename.endswith('.egg'):
             self._python_includes.append(filename)
             # for tests in local mode
-            sys.path.append(os.path.join(SparkFiles.getRootDirectory(), filename))
+            sys.path.insert(1, os.path.join(SparkFiles.getRootDirectory(), filename))
 
     def setCheckpointDir(self, dirName):
         """