Fixes issue #19506: Use a memoryview to avoid a data copy when piping data
to stdin within subprocess.Popen.communicate. 5-10% less cpu usage.
diff --git a/Lib/subprocess.py b/Lib/subprocess.py
index 0942d94..e7f39fe 100644
--- a/Lib/subprocess.py
+++ b/Lib/subprocess.py
@@ -1562,6 +1562,9 @@
self._save_input(input)
+ if self._input:
+ input_view = memoryview(self._input)
+
with _PopenSelector() as selector:
if self.stdin and input:
selector.register(self.stdin, selectors.EVENT_WRITE)
@@ -1583,8 +1586,8 @@
for key, events in ready:
if key.fileobj is self.stdin:
- chunk = self._input[self._input_offset :
- self._input_offset + _PIPE_BUF]
+ chunk = input_view[self._input_offset :
+ self._input_offset + _PIPE_BUF]
try:
self._input_offset += os.write(key.fd, chunk)
except OSError as e: