Issue #9670: Increase the default stack size for secondary threads on

Mac OS X and FreeBSD to reduce the chances of a crash instead of a
"maximum recursion depth" RuntimeError exception.
(Patch by Ronald Oussoren)

3 files changed, 47 insertions, 0 deletions

diff --git a/Lib/test/test_threading.py b/Lib/test/test_threading.py
index f977a7f..75235ad 100644
--- a/Lib/test/test_threading.py
+++ b/Lib/test/test_threading.py
@@ -650,6 +650,36 @@ class ThreadingExceptionTests(unittest.TestCase):
         thread.start()
         self.assertRaises(RuntimeError, setattr, thread, "daemon", True)
 
+    def test_recursion_limit(self):
+        # Issue 9670
+        # test that excessive recursion within a non-main thread causes
+        # an exception rather than crashing the interpreter on platforms
+        # like Mac OS X or FreeBSD which have small default stack sizes
+        # for threads
+        script = """if True:
+            import threading
+
+            def recurse():
+                return recurse()
+
+            def outer():
+                try:
+                    recurse()
+                except RuntimeError:
+                    pass
+
+            w = threading.Thread(target=outer)
+            w.start()
+            w.join()
+            print('end of main thread')
+            """
+        expected_output = "end of main thread\n"
+        p = subprocess.Popen([sys.executable, "-c", script],
+                             stdout=subprocess.PIPE)
+        stdout, stderr = p.communicate()
+        data = stdout.decode().replace('\r', '')
+        self.assertEqual(p.returncode, 0, "Unexpected error")
+        self.assertEqual(data, expected_output)
 
 class LockTests(lock_tests.LockTests):
     locktype = staticmethod(threading.Lock)
diff --git a/Misc/NEWS b/Misc/NEWS
index 5307fe8..81586f0 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -10,6 +10,11 @@ What's New in Python 3.1.4?
 Core and Builtins
 -----------------
 
+- Issue #9670: Increase the default stack size for secondary threads on
+  Mac OS X and FreeBSD to reduce the chances of a crash instead of a
+  "maximum recursion depth" RuntimeError exception.
+  (original patch by Ronald Oussoren)
+
 - Issue #11650: PyOS_StdioReadline() retries fgets() if it was interrupted
   (EINTR), for example if the program is stopped with CTRL+z on Mac OS X. Patch
   written by Charles-Francois Natali.
diff --git a/Python/thread_pthread.h b/Python/thread_pthread.h
index 32fd2d0..ffe2c77 100644
--- a/Python/thread_pthread.h
+++ b/Python/thread_pthread.h
@@ -18,6 +18,18 @@
 #ifndef THREAD_STACK_SIZE
 #define THREAD_STACK_SIZE       0       /* use default stack size */
 #endif
+
+#if (defined(__APPLE__) || defined(__FreeBSD__)) && defined(THREAD_STACK_SIZE) && THREAD_STACK_SIZE == 0
+   /* The default stack size for new threads on OSX is small enough that
+    * we'll get hard crashes instead of 'maximum recursion depth exceeded'
+    * exceptions.
+    *
+    * The default stack size below is the minimal stack size where a
+    * simple recursive function doesn't cause a hard crash.
+    */
+#undef  THREAD_STACK_SIZE
+#define THREAD_STACK_SIZE       0x100000
+#endif
 /* for safety, ensure a viable minimum stacksize */
 #define THREAD_STACK_MIN        0x8000  /* 32kB */
 #else  /* !_POSIX_THREAD_ATTR_STACKSIZE */