From e595c8d08a20a122295af62d5e9cc4116f9727f6 Mon Sep 17 00:00:00 2001
From: Davies Liu <davies.liu@gmail.com>
Date: Thu, 23 Oct 2014 17:20:00 -0700
Subject: [PATCH] [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()
---
.../scala/org/apache/spark/SparkEnv.scala | 2 ++
.../apache/spark/api/python/PythonRDD.scala | 11 ++++++++++-
python/pyspark/daemon.py | 5 ++++-
python/pyspark/serializers.py | 1 +
python/pyspark/tests.py | 19 ++++++++++++++++++-
python/pyspark/worker.py | 11 +++++++++--
6 files changed, 44 insertions(+), 5 deletions(-)
diff --git a/core/src/main/scala/org/apache/spark/SparkEnv.scala b/core/src/main/scala/org/apache/spark/SparkEnv.scala
index aba713cb42..906a00b0bd 100644
--- a/core/src/main/scala/org/apache/spark/SparkEnv.scala
+++ b/core/src/main/scala/org/apache/spark/SparkEnv.scala
@@ -68,6 +68,7 @@ class SparkEnv (
val shuffleMemoryManager: ShuffleMemoryManager,
val conf: SparkConf) extends Logging {
+ private[spark] var isStopped = false
private val pythonWorkers = mutable.HashMap[(String, Map[String, String]), PythonWorkerFactory]()
// A general, soft-reference map for metadata needed during HadoopRDD split computation
@@ -75,6 +76,7 @@ class SparkEnv (
private[spark] val hadoopJobMetadata = new MapMaker().softValues().makeMap[String, Any]()
private[spark] def stop() {
+ isStopped = true
pythonWorkers.foreach { case(key, worker) => worker.stop() }
Option(httpFileServer).foreach(_.stop())
mapOutputTracker.stop()
diff --git a/core/src/main/scala/org/apache/spark/api/python/PythonRDD.scala b/core/src/main/scala/org/apache/spark/api/python/PythonRDD.scala
index 29ca751519..163dca6cad 100644
--- a/core/src/main/scala/org/apache/spark/api/python/PythonRDD.scala
+++ b/core/src/main/scala/org/apache/spark/api/python/PythonRDD.scala
@@ -75,6 +75,7 @@ private[spark] class PythonRDD(
var complete_cleanly = false
context.addTaskCompletionListener { context =>
writerThread.shutdownOnTaskCompletion()
+ writerThread.join()
if (reuse_worker && complete_cleanly) {
env.releasePythonWorker(pythonExec, envVars.toMap, worker)
} else {
@@ -145,7 +146,9 @@ private[spark] class PythonRDD(
stream.readFully(update)
accumulator += Collections.singletonList(update)
}
- complete_cleanly = true
+ if (stream.readInt() == SpecialLengths.END_OF_STREAM) {
+ complete_cleanly = true
+ }
null
}
} catch {
@@ -154,6 +157,10 @@ private[spark] class PythonRDD(
logDebug("Exception thrown after task interruption", e)
throw new TaskKilledException
+ case e: Exception if env.isStopped =>
+ logDebug("Exception thrown after context is stopped", e)
+ null // exit silently
+
case e: Exception if writerThread.exception.isDefined =>
logError("Python worker exited unexpectedly (crashed)", e)
logError("This may have been caused by a prior exception:", writerThread.exception.get)
@@ -235,6 +242,7 @@ private[spark] class PythonRDD(
// Data values
PythonRDD.writeIteratorToStream(firstParent.iterator(split, context), dataOut)
dataOut.writeInt(SpecialLengths.END_OF_DATA_SECTION)
+ dataOut.writeInt(SpecialLengths.END_OF_STREAM)
dataOut.flush()
} catch {
case e: Exception if context.isCompleted || context.isInterrupted =>
@@ -306,6 +314,7 @@ private object SpecialLengths {
val END_OF_DATA_SECTION = -1
val PYTHON_EXCEPTION_THROWN = -2
val TIMING_DATA = -3
+ val END_OF_STREAM = -4
}
private[spark] object PythonRDD extends Logging {
diff --git a/python/pyspark/daemon.py b/python/pyspark/daemon.py
index 64d6202acb..dbb34775d9 100644
--- a/python/pyspark/daemon.py
+++ b/python/pyspark/daemon.py
@@ -26,7 +26,7 @@ import time
import gc
from errno import EINTR, ECHILD, EAGAIN
from socket import AF_INET, SOCK_STREAM, SOMAXCONN
-from signal import SIGHUP, SIGTERM, SIGCHLD, SIG_DFL, SIG_IGN
+from signal import SIGHUP, SIGTERM, SIGCHLD, SIG_DFL, SIG_IGN, SIGINT
from pyspark.worker import main as worker_main
from pyspark.serializers import read_int, write_int
@@ -46,6 +46,9 @@ def worker(sock):
signal.signal(SIGHUP, SIG_DFL)
signal.signal(SIGCHLD, SIG_DFL)
signal.signal(SIGTERM, SIG_DFL)
+ # restore the handler for SIGINT,
+ # it's useful for debugging (show the stacktrace before exit)
+ signal.signal(SIGINT, signal.default_int_handler)
# Read the socket using fdopen instead of socket.makefile() because the latter
# seems to be very slow; note that we need to dup() the file descriptor because
diff --git a/python/pyspark/serializers.py b/python/pyspark/serializers.py
index 08a0f0d8ff..904bd9f265 100644
--- a/python/pyspark/serializers.py
+++ b/python/pyspark/serializers.py
@@ -80,6 +80,7 @@ class SpecialLengths(object):
END_OF_DATA_SECTION = -1
PYTHON_EXCEPTION_THROWN = -2
TIMING_DATA = -3
+ END_OF_STREAM = -4
class Serializer(object):
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):
diff --git a/python/pyspark/worker.py b/python/pyspark/worker.py
index 8257dddfee..2bdccb5e93 100644
--- a/python/pyspark/worker.py
+++ b/python/pyspark/worker.py
@@ -57,7 +57,7 @@ def main(infile, outfile):
boot_time = time.time()
split_index = read_int(infile)
if split_index == -1: # for unit tests
- return
+ exit(-1)
# initialize global state
shuffle.MemoryBytesSpilled = 0
@@ -111,7 +111,6 @@ def main(infile, outfile):
try:
write_int(SpecialLengths.PYTHON_EXCEPTION_THROWN, outfile)
write_with_length(traceback.format_exc(), outfile)
- outfile.flush()
except IOError:
# JVM close the socket
pass
@@ -131,6 +130,14 @@ def main(infile, outfile):
for (aid, accum) in _accumulatorRegistry.items():
pickleSer._write_with_length((aid, accum._value), outfile)
+ # check end of stream
+ if read_int(infile) == SpecialLengths.END_OF_STREAM:
+ write_int(SpecialLengths.END_OF_STREAM, outfile)
+ else:
+ # write a different value to tell JVM to not reuse this worker
+ write_int(SpecialLengths.END_OF_DATA_SECTION, outfile)
+ exit(-1)
+
if __name__ == '__main__':
# Read a local port to connect to from stdin
--
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