add shield to _make_subprocess_transport

Author: kumaraditya303

Lib/asyncio/unix_events.py

@@ -197,24 +197,30 @@ def _make_write_pipe_transport(self, pipe, protocol, waiter=None,
     async def _make_subprocess_transport(self, protocol, args, shell,
                                          stdin, stdout, stderr, bufsize,
                                          extra=None, **kwargs):
-        watcher = self._watcher
-        waiter = self.create_future()
-        transp = _UnixSubprocessTransport(self, protocol, args, shell,
-                                        stdin, stdout, stderr, bufsize,
-                                        waiter=waiter, extra=extra,
-                                        **kwargs)
-        watcher.add_child_handler(transp.get_pid(),
-                                self._child_watcher_callback, transp)
-        try:
-            await waiter
-        except (SystemExit, KeyboardInterrupt):
-            raise
-        except BaseException:
-            transp.close()
-            await transp._wait()
-            raise
+        async def shielded():
+            # See https://github.com/python/cpython/issues/103847
+            # This code needs to be shielded to prevent cancellation
+            # as _UnixSubprocessTransport doesn't handle it properly.
+            watcher = self._watcher
+            waiter = self.create_future()
+            transp = _UnixSubprocessTransport(self, protocol, args, shell,
+                                            stdin, stdout, stderr, bufsize,
+                                            waiter=waiter, extra=extra,
+                                            **kwargs)
+            watcher.add_child_handler(transp.get_pid(),
+                                    self._child_watcher_callback, transp)
+            try:
+                await waiter
+            except (SystemExit, KeyboardInterrupt):
+                raise
+            except BaseException:
+                transp.close()
+                await transp._wait()
+                raise
+
+            return transp
 
-        return transp
+        return await tasks.shield(shielded())
 
     def _child_watcher_callback(self, pid, returncode, transp):
         self.call_soon_threadsafe(transp._process_exited, returncode)