Issue #13812: When a multiprocessing Process child raises an exception, flush stderr after printing the exception traceback.
diff --git a/Lib/multiprocessing/forking.py b/Lib/multiprocessing/forking.py
index cc7c326..4e24d6a 100644
--- a/Lib/multiprocessing/forking.py
+++ b/Lib/multiprocessing/forking.py
@@ -124,8 +124,6 @@
import random
random.seed()
code = process_obj._bootstrap()
- sys.stdout.flush()
- sys.stderr.flush()
os._exit(code)
def poll(self, flag=os.WNOHANG):
diff --git a/Lib/multiprocessing/process.py b/Lib/multiprocessing/process.py
index 5987af9..2b61ee9 100644
--- a/Lib/multiprocessing/process.py
+++ b/Lib/multiprocessing/process.py
@@ -275,16 +275,17 @@
exitcode = e.args[0]
else:
sys.stderr.write(e.args[0] + '\n')
- sys.stderr.flush()
exitcode = 1
except:
exitcode = 1
import traceback
sys.stderr.write('Process %s:\n' % self.name)
- sys.stderr.flush()
traceback.print_exc()
+ finally:
+ util.info('process exiting with exitcode %d' % exitcode)
+ sys.stdout.flush()
+ sys.stderr.flush()
- util.info('process exiting with exitcode %d' % exitcode)
return exitcode
#
diff --git a/Lib/test/test_multiprocessing.py b/Lib/test/test_multiprocessing.py
index de894f3..8edb420 100644
--- a/Lib/test/test_multiprocessing.py
+++ b/Lib/test/test_multiprocessing.py
@@ -367,6 +367,29 @@
uppercaser.stop()
uppercaser.join()
+ def test_stderr_flush(self):
+ # sys.stderr is flushed at process shutdown (issue #13812)
+ if self.TYPE == "threads":
+ return
+
+ testfn = test.support.TESTFN
+ self.addCleanup(test.support.unlink, testfn)
+ proc = self.Process(target=self._test_stderr_flush, args=(testfn,))
+ proc.start()
+ proc.join()
+ with open(testfn, 'r') as f:
+ err = f.read()
+ # The whole traceback was printed
+ self.assertIn("ZeroDivisionError", err)
+ self.assertIn("test_multiprocessing.py", err)
+ self.assertIn("1/0 # MARKER", err)
+
+ @classmethod
+ def _test_stderr_flush(cls, testfn):
+ sys.stderr = open(testfn, 'w')
+ 1/0 # MARKER
+
+
#
#
#