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()
diff --git a/Python/bootstrap_hash.c b/Python/bootstrap_hash.c
index 9fd5cfb..073b2ea 100644
--- a/Python/bootstrap_hash.c
+++ b/Python/bootstrap_hash.c
@@ -301,10 +301,15 @@
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,