Avoid overwriting deserialized accumulator.

python/pyspark/accumulators.py

@@ -110,10 +110,14 @@
 
 def _deserialize_accumulator(aid, zero_value, accum_param):
     from pyspark.accumulators import _accumulatorRegistry
-    accum = Accumulator(aid, zero_value, accum_param)
-    accum._deserialized = True
-    _accumulatorRegistry[aid] = accum
-    return accum
+    # If this certain accumulator was deserialized, don't overwrite it.
+    if aid in _accumulatorRegistry:
+        return _accumulatorRegistry[aid]
+    else:
+        accum = Accumulator(aid, zero_value, accum_param)
+        accum._deserialized = True
+        _accumulatorRegistry[aid] = accum
+        return accum
 
 
 class Accumulator(object):

python/pyspark/sql/tests.py

@@ -2932,6 +2932,31 @@ def test_create_dateframe_from_pandas_with_dst(self):
                 os.environ['TZ'] = orig_env_tz
             time.tzset()
 
+    # SPARK-25591
+    def test_same_accumulator_in_udfs(self):
+        from pyspark.sql.functions import udf
+
+        data_schema = StructType([StructField("a", IntegerType(), True),
+                                  StructField("b", IntegerType(), True)])
+        data = self.spark.createDataFrame([[1, 2]], schema=data_schema)
+
+        test_accum = self.sc.accumulator(0)
+
+        def first_udf(x):
+            test_accum.add(1)
+            return x
+
+        def second_udf(x):
+            test_accum.add(100)
+            return x
+
+        func_udf = udf(first_udf, IntegerType())
+        func_udf2 = udf(second_udf, IntegerType())
+        data = data.withColumn("out1", func_udf(data["a"]))
+        data = data.withColumn("out2", func_udf2(data["b"]))
+        data.collect()
+        self.assertEqual(test_accum.value, 101)
+
 
 class HiveSparkSubmitTests(SparkSubmitTests):