[Python-checkins] cpython (merge 3.2 -> default): Issue #1856: Avoid crashes and lockups when daemon threads run while the

Wed May 4 20:05:07 CEST 2011

http://hg.python.org/cpython/rev/c892b0321d23
changeset: 69833:c892b0321d23
parent: 69831:29504a0ab56d
parent: 69832:2a19d09b08f8
user: Antoine Pitrou <solipsis at pitrou.net>
date: Wed May 04 20:04:29 2011 +0200
summary:
 Issue #1856: Avoid crashes and lockups when daemon threads run while the
interpreter is shutting down; instead, these threads are now killed when
they try to take the GIL.
files:
 Include/pythonrun.h | 2 +
 Lib/test/test_threading.py | 45 +++++++++++++++++++++++++-
 Misc/NEWS | 4 ++
 Python/ceval.c | 6 +++
 Python/pythonrun.c | 15 ++++++--
 Python/thread_pthread.h | 4 +-
 6 files changed, 69 insertions(+), 7 deletions(-)

diff --git a/Include/pythonrun.h b/Include/pythonrun.h
--- a/Include/pythonrun.h
+++ b/Include/pythonrun.h
@@ -211,6 +211,8 @@
 PyAPI_FUNC(void) PyFloat_Fini(void);
 PyAPI_FUNC(void) PyOS_FiniInterrupts(void);
 PyAPI_FUNC(void) _PyGC_Fini(void);
+
+PyAPI_DATA(PyThreadState *) _Py_Finalizing;
 #endif
 
 /* Stuff with no proper home (yet) */
diff --git a/Lib/test/test_threading.py b/Lib/test/test_threading.py
--- a/Lib/test/test_threading.py
+++ b/Lib/test/test_threading.py
@@ -12,6 +12,7 @@
 import weakref
 import os
 import subprocess
+from test.script_helper import assert_python_ok
 
 from test import lock_tests
 
@@ -471,7 +472,6 @@
 """
 self._run_and_join(script)
 
-
 @unittest.skipUnless(hasattr(os, 'fork'), "needs os.fork()")
 def test_2_join_in_forked_process(self):
 # Like the test above, but from a forked interpreter
@@ -663,6 +663,49 @@
 output = "end of worker thread\nend of main thread\n"
 self.assertScriptHasOutput(script, output)
 
+ def test_6_daemon_threads(self):
+ # Check that a daemon thread cannot crash the interpreter on shutdown
+ # by manipulating internal structures that are being disposed of in
+ # the main thread.
+ script = """if True:
+ import os
+ import random
+ import sys
+ import time
+ import threading
+
+ thread_has_run = set()
+
+ def random_io():
+ '''Loop for a while sleeping random tiny amounts and doing some I/O.'''
+ blank = b'x' * 200
+ while True:
+ in_f = open(os.__file__, 'r')
+ stuff = in_f.read(200)
+ null_f = open(os.devnull, 'w')
+ null_f.write(stuff)
+ time.sleep(random.random() / 1995)
+ null_f.close()
+ in_f.close()
+ thread_has_run.add(threading.current_thread())
+
+ def main():
+ count = 0
+ for _ in range(40):
+ new_thread = threading.Thread(target=random_io)
+ new_thread.daemon = True
+ new_thread.start()
+ count += 1
+ while len(thread_has_run) < count:
+ time.sleep(0.001)
+ # Trigger process shutdown
+ sys.exit(0)
+
+ main()
+ """
+ rc, out, err = assert_python_ok('-c', script)
+ self.assertFalse(err)
+
 
 class ThreadingExceptionTests(BaseTestCase):
 # A RuntimeError should be raised if Thread.start() is called
diff --git a/Misc/NEWS b/Misc/NEWS
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -10,6 +10,10 @@
 Core and Builtins
 -----------------
 
+- Issue #1856: Avoid crashes and lockups when daemon threads run while the
+ interpreter is shutting down; instead, these threads are now killed when
+ they try to take the GIL.
+
 - Issue #11849: Make it more likely for the system allocator to release
 free()d memory arenas on glibc-based systems. Patch by Charles-François
 Natali.
diff --git a/Python/ceval.c b/Python/ceval.c
--- a/Python/ceval.c
+++ b/Python/ceval.c
@@ -440,6 +440,12 @@
 if (gil_created()) {
 int err = errno;
 take_gil(tstate);
+ /* _Py_Finalizing is protected by the GIL */
+ if (_Py_Finalizing && tstate != _Py_Finalizing) {
+ drop_gil(tstate);
+ PyThread_exit_thread();
+ assert(0); /* unreachable */
+ }
 errno = err;
 }
 #endif
diff --git a/Python/pythonrun.c b/Python/pythonrun.c
--- a/Python/pythonrun.c
+++ b/Python/pythonrun.c
@@ -93,6 +93,8 @@
 int Py_NoUserSiteDirectory = 0; /* for -s and site.py */
 int Py_UnbufferedStdioFlag = 0; /* Unbuffered binary std{in,out,err} */
 
+PyThreadState *_Py_Finalizing = NULL;
+
 /* PyModule_GetWarningsModule is no longer necessary as of 2.6
 since _warnings is builtin. This API should not be used. */
 PyObject *
@@ -191,6 +193,7 @@
 if (initialized)
 return;
 initialized = 1;
+ _Py_Finalizing = NULL;
 
 #if defined(HAVE_LANGINFO_H) && defined(HAVE_SETLOCALE)
 /* Set up the LC_CTYPE locale, so we can obtain
@@ -395,15 +398,19 @@
 * the threads created via Threading.
 */
 call_py_exitfuncs();
+
+ /* Get current thread state and interpreter pointer */
+ tstate = PyThreadState_GET();
+ interp = tstate->interp;
+
+ /* Remaining threads (e.g. daemon threads) will automatically exit
+ after taking the GIL (in PyEval_RestoreThread()). */
+ _Py_Finalizing = tstate;
 initialized = 0;
 
 /* Flush stdout+stderr */
 flush_std_files();
 
- /* Get current thread state and interpreter pointer */
- tstate = PyThreadState_GET();
- interp = tstate->interp;
-
 /* Disable signal handling */
 PyOS_FiniInterrupts();
 
diff --git a/Python/thread_pthread.h b/Python/thread_pthread.h
--- a/Python/thread_pthread.h
+++ b/Python/thread_pthread.h
@@ -244,9 +244,9 @@
 PyThread_exit_thread(void)
 {
 dprintf(("PyThread_exit_thread called\n"));
- if (!initialized) {
+ if (!initialized)
 exit(0);
- }
+ pthread_exit(0);
 }
 
 #ifdef USE_SEMAPHORES
-- 
Repository URL: http://hg.python.org/cpython
