[SPARK-3993] [PySpark] fix bug while reuse worker after take()

After take(), maybe there are some garbage left in the socket, then next task assigned to this worker will hang because of corrupted data.

We should make sure the socket is clean before reuse it, write END_OF_STREAM at the end, and check it after read out all result from python.

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

Closes #2838 from davies/fix_reuse and squashes the following commits:

8872914 [Davies Liu] fix tests
660875b [Davies Liu] fix bug while reuse worker after take()

1 files changed, 18 insertions, 1 deletions

diff --git a/python/pyspark/tests.py b/python/pyspark/tests.py
index 1a8e4150e6..7a2107ec32 100644
--- a/python/pyspark/tests.py
+++ b/python/pyspark/tests.py
@@ -31,7 +31,7 @@ import tempfile
 import time
 import zipfile
 import random
-from platform import python_implementation
+import threading
 
 if sys.version_info[:2] <= (2, 6):
     try:
@@ -1380,6 +1380,23 @@ class WorkerTests(PySparkTestCase):
         self.assertEqual(sum(range(100)), acc2.value)
         self.assertEqual(sum(range(100)), acc1.value)
 
+    def test_reuse_worker_after_take(self):
+        rdd = self.sc.parallelize(range(100000), 1)
+        self.assertEqual(0, rdd.first())
+
+        def count():
+            try:
+                rdd.count()
+            except Exception:
+                pass
+
+        t = threading.Thread(target=count)
+        t.daemon = True
+        t.start()
+        t.join(5)
+        self.assertTrue(not t.isAlive())
+        self.assertEqual(100000, rdd.count())
+
 
 class SparkSubmitTests(unittest.TestCase):