bpo-32186: Release the GIL during lseek and fstat (#4652)
In _io_FileIO_readall_impl(), lseek() and _Py_fstat_noraise() were called
without releasing the GIL. This can cause all threads to hang for
unlimited time when calling FileIO.read() and the NFS server is not
accessible.
diff --git a/Modules/_io/fileio.c b/Modules/_io/fileio.c
index b6755b8..269142c 100644
--- a/Modules/_io/fileio.c
+++ b/Modules/_io/fileio.c
@@ -683,10 +683,12 @@
Py_ssize_t bytes_read = 0;
Py_ssize_t n;
size_t bufsize;
+ int fstat_result;
if (self->fd < 0)
return err_closed();
+ Py_BEGIN_ALLOW_THREADS
_Py_BEGIN_SUPPRESS_IPH
#ifdef MS_WINDOWS
pos = _lseeki64(self->fd, 0L, SEEK_CUR);
@@ -694,8 +696,10 @@
pos = lseek(self->fd, 0L, SEEK_CUR);
#endif
_Py_END_SUPPRESS_IPH
+ fstat_result = _Py_fstat_noraise(self->fd, &status);
+ Py_END_ALLOW_THREADS
- if (_Py_fstat_noraise(self->fd, &status) == 0)
+ if (fstat_result == 0)
end = status.st_size;
else
end = (Py_off_t)-1;