[Python-checkins] bpo-33021: Release the GIL during fstat() calls (GH-6019)
Antoine Pitrou
webhook-mailer at python.org
Sun Mar 11 19:39:25 EDT 2018
https://github.com/python/cpython/commit/4484f9dca9149da135bbae035f10a50d20d1cbbb
commit: 4484f9dca9149da135bbae035f10a50d20d1cbbb
branch: master
author: Nir Soffer <nirsof at gmail.com>
committer: Antoine Pitrou <pitrou at free.fr>
date: 2018-03-12T00:39:22+01:00
summary:
bpo-33021: Release the GIL during fstat() calls (GH-6019)
fstat may block for long time if the file descriptor is on a
non-responsive NFS server, hanging all threads. Most fstat() calls are
handled by _Py_fstat(), releasing the GIL internally, but but
_Py_fstat_noraise() does not release the GIL, and most calls release the
GIL explicitly around it.
This patch fixes last 2 calls to _Py_fstat_no_raise(), avoiding hangs
when calling:
- mmap.mmap()
- os.urandom()
- random.seed()
files:
A Misc/NEWS.d/next/Library/2018-03-12-00-27-56.bpo-33021.m19B9T.rst
M Modules/mmapmodule.c
M Python/bootstrap_hash.c
diff --git a/Misc/NEWS.d/next/Library/2018-03-12-00-27-56.bpo-33021.m19B9T.rst b/Misc/NEWS.d/next/Library/2018-03-12-00-27-56.bpo-33021.m19B9T.rst
new file mode 100644
index 000000000000..50dfafe600d8
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2018-03-12-00-27-56.bpo-33021.m19B9T.rst
@@ -0,0 +1,2 @@
+Release the GIL during fstat() calls, avoiding hang of all threads when
+calling mmap.mmap(), os.urandom(), and random.seed(). Patch by Nir Soffer.
diff --git a/Modules/mmapmodule.c b/Modules/mmapmodule.c
index 6cf454573e93..6abdc71bbb82 100644
--- a/Modules/mmapmodule.c
+++ b/Modules/mmapmodule.c
@@ -1050,6 +1050,7 @@ static PyObject *
new_mmap_object(PyTypeObject *type, PyObject *args, PyObject *kwdict)
{
struct _Py_stat_struct status;
+ int fstat_result;
mmap_object *m_obj;
Py_ssize_t map_size;
off_t offset = 0;
@@ -1115,8 +1116,14 @@ new_mmap_object(PyTypeObject *type, PyObject *args, PyObject *kwdict)
if (fd != -1)
(void)fcntl(fd, F_FULLFSYNC);
#endif
- if (fd != -1 && _Py_fstat_noraise(fd, &status) == 0
- && S_ISREG(status.st_mode)) {
+
+ if (fd != -1) {
+ Py_BEGIN_ALLOW_THREADS
+ fstat_result = _Py_fstat_noraise(fd, &status);
+ Py_END_ALLOW_THREADS
+ }
+
+ if (fd != -1 && fstat_result == 0 && S_ISREG(status.st_mode)) {
if (map_size == 0) {
if (status.st_size == 0) {
PyErr_SetString(PyExc_ValueError,
diff --git a/Python/bootstrap_hash.c b/Python/bootstrap_hash.c
index 9fd5cfb200ea..073b2ea8dbda 100644
--- a/Python/bootstrap_hash.c
+++ b/Python/bootstrap_hash.c
@@ -301,10 +301,15 @@ dev_urandom(char *buffer, Py_ssize_t size, int raise)
if (raise) {
struct _Py_stat_struct st;
+ int fstat_result;
if (urandom_cache.fd >= 0) {
+ Py_BEGIN_ALLOW_THREADS
+ fstat_result = _Py_fstat_noraise(urandom_cache.fd, &st);
+ Py_END_ALLOW_THREADS
+
/* Does the fd point to the same thing as before? (issue #21207) */
- if (_Py_fstat_noraise(urandom_cache.fd, &st)
+ if (fstat_result
|| st.st_dev != urandom_cache.st_dev
|| st.st_ino != urandom_cache.st_ino) {
/* Something changed: forget the cached fd (but don't close it,
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