handle asynchronous exceptions when creating SubprocessTransport

Author: Martiusweb

asyncio/base_subprocess.py

@@ -26,6 +26,7 @@ def __init__(self, loop, protocol, args, shell,
         self._pending_calls = collections.deque()
         self._pipes = {}
         self._finished = False
+        self._failed_before_start = False
 
         if stdin == subprocess.PIPE:
             self._pipes[0] = None
@@ -47,7 +48,12 @@ def _create_child(self, waiter, args, shell, stdin, stdout, stderr,
                 start = self._start(args=args, shell=shell, stdin=stdin,
                                     stdout=stdout, stderr=stderr,
                                     bufsize=bufsize, **start_kwargs)
+            except:
+                self._failed_before_start = True
+                self.close()
+                raise
 
+            try:
                 if start is not None:
                     # _start is not required to be a coroutine
                     yield from start
@@ -255,6 +261,12 @@ def _wait(self):
         """Wait until the process exit and return the process return code.
 
         This method is a coroutine."""
+        if self._failed_before_start:
+            # Let loop._make_subprocess_transport() call transport._wait() when
+            # an exception is raised asynchronously during the setup of the
+            # transport, it garantees that necessary cleanup will be performed.
+            return
+
         if self._returncode is not None:
             return self._returncode
 

asyncio/unix_events.py

@@ -713,10 +713,6 @@ def _check_exec_result(self, pid, returncode, orig_executable, cwd,
 
 
 class _UnixSubprocessTransport(base_subprocess.BaseSubprocessTransport):
-    def __init__(self, *args, **kwargs):
-        super().__init__(*args, **kwargs)
-        self._failed_before_exec = False
-
     @coroutine
     def _start(self, args, shell, stdin, stdout, stderr, bufsize, **kwargs):
         with events.get_child_watcher() as watcher:
@@ -742,7 +738,7 @@ def _start(self, args, shell, stdin, stdout, stderr, bufsize, **kwargs):
                     universal_newlines=False, bufsize=bufsize, **kwargs)
                 yield from exec_waiter
             except:
-                self._failed_before_exec = True
+                self._failed_before_start = True
                 # TODO stdin is probably closed by proc, but what about stdin_w
                 # so far? check this
                 if stdin_w is not None:
@@ -758,17 +754,6 @@ def _start(self, args, shell, stdin, stdout, stderr, bufsize, **kwargs):
     def _child_watcher_callback(self, pid, returncode):
         self._loop.call_soon_threadsafe(self._process_exited, returncode)
 
-    @coroutine
-    def _wait(self):
-        if self._failed_before_exec:
-            # let loop._make_subprocess_transport() call transport._wait() when
-            # an excpetion is raised asynchronously during the setup of the
-            # transport, which garantees that necessary cleanup will be
-            # performed
-            return
-        else:
-            return (yield from super()._wait())
-
 
 class AbstractChildWatcher:
     """Abstract base class for monitoring child processes.