[Python-checkins] bpo-31516: current_thread() should not return a dummy thread at shutdown (#3673)

Mon Oct 2 10:42:18 EDT 2017

https://github.com/python/cpython/commit/1023dbbcb7f05e76053486ae7ef7f73b4cdc5398
commit: 1023dbbcb7f05e76053486ae7ef7f73b4cdc5398
branch: master
author: Antoine Pitrou <pitrou at free.fr>
committer: GitHub <noreply at github.com>
date: 2017年10月02日T16:42:15+02:00
summary:
bpo-31516: current_thread() should not return a dummy thread at shutdown (#3673)
bpo-31516: current_thread() should not return a dummy thread at shutdown
files:
A Misc/NEWS.d/next/Library/2017-09-20-18-43-01.bpo-31516.23Yuq3.rst
M Lib/test/test_threading.py
M Lib/threading.py

diff --git a/Lib/test/test_threading.py b/Lib/test/test_threading.py
index f7c3680bda3..6e1ae06f792 100644
--- a/Lib/test/test_threading.py
+++ b/Lib/test/test_threading.py
@@ -547,6 +547,35 @@ def f():
 self.assertEqual(err, b"")
 self.assertEqual(data, "Thread-1\nTrue\nTrue\n")
 
+ def test_main_thread_during_shutdown(self):
+ # bpo-31516: current_thread() should still point to the main thread
+ # at shutdown
+ code = """if 1:
+ import gc, threading
+
+ main_thread = threading.current_thread()
+ assert main_thread is threading.main_thread() # sanity check
+
+ class RefCycle:
+ def __init__(self):
+ self.cycle = self
+
+ def __del__(self):
+ print("GC:",
+ threading.current_thread() is main_thread,
+ threading.main_thread() is main_thread,
+ threading.enumerate() == [main_thread])
+
+ RefCycle()
+ gc.collect() # sanity check
+ x = RefCycle()
+ """
+ _, out, err = assert_python_ok("-c", code)
+ data = out.decode()
+ self.assertEqual(err, b"")
+ self.assertEqual(data.splitlines(),
+ ["GC: True True True"] * 2)
+
 def test_tstate_lock(self):
 # Test an implementation detail of Thread objects.
 started = _thread.allocate_lock()
diff --git a/Lib/threading.py b/Lib/threading.py
index e4bf974495b..418116faceb 100644
--- a/Lib/threading.py
+++ b/Lib/threading.py
@@ -1158,8 +1158,8 @@ def run(self):
 self.function(*self.args, **self.kwargs)
 self.finished.set()
 
+
 # Special thread class to represent the main thread
-# This is garbage collected through an exit handler
 
 class _MainThread(Thread):
 
@@ -1272,7 +1272,6 @@ def _shutdown():
 while t:
 t.join()
 t = _pickSomeNonDaemonThread()
- _main_thread._delete()
 
 def _pickSomeNonDaemonThread():
 for t in enumerate():
diff --git a/Misc/NEWS.d/next/Library/2017-09-20-18-43-01.bpo-31516.23Yuq3.rst b/Misc/NEWS.d/next/Library/2017-09-20-18-43-01.bpo-31516.23Yuq3.rst
new file mode 100644
index 00000000000..af48d159fef
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2017-09-20-18-43-01.bpo-31516.23Yuq3.rst
@@ -0,0 +1 @@
+``threading.current_thread()`` should not return a dummy thread at shutdown.
