Optimization for communicate(): If only one of stdin/stdout/stderr is
redirected, using select() or threads is unnecessary.
diff --git a/Lib/subprocess.py b/Lib/subprocess.py
index 382acb6..61effde 100644
--- a/Lib/subprocess.py
+++ b/Lib/subprocess.py
@@ -619,6 +619,33 @@
data = data.replace("\r", "\n")
return data
+ def communicate(self, input=None):
+ """Interact with process: Send data to stdin. Read data from
+ stdout and stderr, until end-of-file is reached. Wait for
+ process to terminate. The optional input argument should be a
+ string to be sent to the child process, or None, if no data
+ should be sent to the child.
+
+ communicate() returns a tuple (stdout, stderr)."""
+
+ # Optimization: If we are only using one pipe, or no pipe at
+ # all, using select() or threads is unnecessary.
+ if [self.stdin, self.stdout, self.stderr].count(None) >= 2:
+ stdout = None
+ stderr = None
+ if self.stdin:
+ if input:
+ self.stdin.write(input)
+ self.stdin.close()
+ elif self.stdout:
+ stdout = self.stdout.read()
+ elif self.stderr:
+ stderr = self.stderr.read()
+ self.wait()
+ return (stdout, stderr)
+
+ return self._communicate(input)
+
if mswindows:
#
@@ -811,14 +838,7 @@
buffer.append(fh.read())
- def communicate(self, input=None):
- """Interact with process: Send data to stdin. Read data from
- stdout and stderr, until end-of-file is reached. Wait for
- process to terminate. The optional input argument should be a
- string to be sent to the child process, or None, if no data
- should be sent to the child.
-
- communicate() returns a tuple (stdout, stderr)."""
+ def _communicate(self, input):
stdout = None # Return
stderr = None # Return
@@ -1066,14 +1086,7 @@
return self.returncode
- def communicate(self, input=None):
- """Interact with process: Send data to stdin. Read data from
- stdout and stderr, until end-of-file is reached. Wait for
- process to terminate. The optional input argument should be a
- string to be sent to the child process, or None, if no data
- should be sent to the child.
-
- communicate() returns a tuple (stdout, stderr)."""
+ def _communicate(self, input):
read_set = []
write_set = []
stdout = None # Return