gh-89977: Keep the GIL for short socket calls (#157981)

Author: methane

Misc/NEWS.d/next/Library/2026-09-23-09-21-25.gh-issue-89977.fmia18.rst

@@ -0,0 +1,3 @@
+Avoid releasing the GIL for :meth:`socket.socket.setblocking`,
+:meth:`socket.socket.getsockname`, :meth:`socket.socket.getpeername`, and
+:func:`socket.gethostname`.

Modules/socketmodule.c

@@ -832,7 +832,6 @@ internal_setblocking(PySocketSockObject *s, int block)
     int delay_flag, new_delay_flag;
 #endif
 
-    Py_BEGIN_ALLOW_THREADS
 #ifndef MS_WINDOWS
 #if (defined(HAVE_SYS_IOCTL_H) && defined(FIONBIO))
     block = !block;
@@ -859,8 +858,6 @@ internal_setblocking(PySocketSockObject *s, int block)
     result = 0;
 
   done:
-    Py_END_ALLOW_THREADS
-
     if (result) {
 #ifndef MS_WINDOWS
         PyErr_SetFromErrno(PyExc_OSError);
@@ -3917,9 +3914,7 @@ _socket_socket_getsockname_impl(PySocketSockObject *s)
     if (!getsockaddrlen(s, &addrlen))
         return NULL;
     memset(&addrbuf, 0, addrlen);
-    Py_BEGIN_ALLOW_THREADS
     res = getsockname(get_sock_fd(s), SAS2SA(&addrbuf), &addrlen);
-    Py_END_ALLOW_THREADS
     if (res < 0)
         return s->errorhandler();
     return makesockaddr(get_sock_fd(s), SAS2SA(&addrbuf), addrlen,
@@ -3952,9 +3947,7 @@ _socket_socket_getpeername_impl(PySocketSockObject *s)
     if (!getsockaddrlen(s, &addrlen))
         return NULL;
     memset(&addrbuf, 0, addrlen);
-    Py_BEGIN_ALLOW_THREADS
     res = getpeername(get_sock_fd(s), SAS2SA(&addrbuf), &addrlen);
-    Py_END_ALLOW_THREADS
     if (res < 0)
         return s->errorhandler();
     return makesockaddr(get_sock_fd(s), SAS2SA(&addrbuf), addrlen,
@@ -5970,9 +5963,7 @@ _socket_gethostname_impl(PyObject *module)
 #else
     char buf[1024];
     int res;
-    Py_BEGIN_ALLOW_THREADS
     res = gethostname(buf, (int) sizeof buf - 1);
-    Py_END_ALLOW_THREADS
     if (res < 0)
         return set_error();
     buf[sizeof buf - 1] = '\0';