On Tue, Oct 6, 2015, at 19:12, raymond.hettinger wrote:

https://hg.python.org/cpython/rev/37aee118e1a3 changeset: 98578:37aee118e1a3 branch: 2.7 parent: 98572:60c44a09c5fc user: Raymond Hettinger date: Tue Oct 06 23:12:02 2015 -0400 summary: Backport early-out 91259f061cfb to reduce the cost of bb1a2944bcb6

files: Modules/_collectionsmodule.c | 6 +++++- 1 files changed, 5 insertions(+), 1 deletions(-)

diff --git a/Modules/_collectionsmodule.c b/Modules/_collectionsmodule.c --- a/Modules/_collectionsmodule.c +++ b/Modules/_collectionsmodule.c @@ -651,6 +651,9 @@ Py_ssize_t n; PyObject *item;

+ if (Py_SIZE(deque) == 0) + return; +

dequeue is not varsized in Python 2.7, so using Py_SIZE() is incorrect.