[SPARK-2580] [PySpark] keep silent in worker if JVM close the socket

During rdd.take(n), JVM will close the socket if it had got enough data, the Python worker should keep silent in this case.

In the same time, the worker should not print the trackback into stderr if it send the traceback to JVM successfully.

Author: Davies Liu <[email protected]>

Closes apache#1625 from davies/error and squashes the following commits:

4fbcc6d [Davies Liu] disable log4j during testing when exception is expected.
cc14202 [Davies Liu] keep silent in worker if JVM close the socket

Author: davies

python/pyspark/tests.py

@@ -165,11 +165,17 @@ class TestAddFile(PySparkTestCase):
     def test_add_py_file(self):
         # To ensure that we're actually testing addPyFile's effects, check that
         # this job fails due to `userlibrary` not being on the Python path:
+        # disable logging in log4j temporarily
+        log4j = self.sc._jvm.org.apache.log4j
+        old_level = log4j.LogManager.getRootLogger().getLevel()
+        log4j.LogManager.getRootLogger().setLevel(log4j.Level.FATAL)
         def func(x):
             from userlibrary import UserClass
             return UserClass().hello()
         self.assertRaises(Exception,
                           self.sc.parallelize(range(2)).map(func).first)
+        log4j.LogManager.getRootLogger().setLevel(old_level)
+
         # Add the file, so the job should now succeed:
         path = os.path.join(SPARK_HOME, "python/test_support/userlibrary.py")
         self.sc.addPyFile(path)

python/pyspark/worker.py

@@ -75,14 +75,19 @@ def main(infile, outfile):
         init_time = time.time()
         iterator = deserializer.load_stream(infile)
         serializer.dump_stream(func(split_index, iterator), outfile)
-    except Exception as e:
-        # Write the error to stderr in addition to trying to pass it back to
-        # Java, in case it happened while serializing a record
-        print >> sys.stderr, "PySpark worker failed with exception:"
-        print >> sys.stderr, traceback.format_exc()
-        write_int(SpecialLengths.PYTHON_EXCEPTION_THROWN, outfile)
-        write_with_length(traceback.format_exc(), outfile)
-        sys.exit(-1)
+    except Exception:
+        try:
+            write_int(SpecialLengths.PYTHON_EXCEPTION_THROWN, outfile)
+            write_with_length(traceback.format_exc(), outfile)
+            outfile.flush()
+        except IOError:
+            # JVM close the socket
+            pass
+        except Exception:
+            # Write the error to stderr if it happened while serializing
+            print >> sys.stderr, "PySpark worker failed with exception:"
+            print >> sys.stderr, traceback.format_exc()
+        exit(-1)
     finish_time = time.time()
     report_times(outfile, boot_time, init_time, finish_time)
     # Mark the beginning of the accumulators section of the output