Merged revisions 73825-73826 via svnmerge from
svn+ssh://pythondev@svn.python.org/python/trunk
........
r73825 | gregory.p.smith | 2009-07-03 18:49:29 -0700 (Fri, 03 Jul 2009) | 9 lines
Use select.poll() in subprocess, when available, rather than select() so that
it does not fail when file descriptors are large. Fixes issue3392.
Patch largely contributed by Frank Chu (fpmc) with some improvements by me.
See http://bugs.python.org/issue3392.
........
r73826 | gregory.p.smith | 2009-07-03 18:55:11 -0700 (Fri, 03 Jul 2009) | 2 lines
news entry for r73825
........
Candidate for backporting to release31-maint as it is a bug fix and changes no
public API.
diff --git a/Lib/subprocess.py b/Lib/subprocess.py
index 368ba0e..f7361e1 100644
--- a/Lib/subprocess.py
+++ b/Lib/subprocess.py
@@ -371,6 +371,7 @@
error = IOError
else:
import select
+ _has_poll = hasattr(select, 'poll')
import errno
import fcntl
import pickle
@@ -383,6 +384,11 @@
except:
MAXFD = 256
+# When select or poll has indicated that the file is writable,
+# we can write up to _PIPE_BUF bytes without risk of blocking.
+# POSIX defines PIPE_BUF as >= 512.
+_PIPE_BUF = getattr(select, 'PIPE_BUF', 512)
+
_active = []
def _cleanup():
@@ -1173,19 +1179,103 @@
def _communicate(self, input):
+ if self.stdin:
+ # Flush stdio buffer. This might block, if the user has
+ # been writing to .stdin in an uncontrolled fashion.
+ self.stdin.flush()
+ if not input:
+ self.stdin.close()
+
+ if _has_poll:
+ stdout, stderr = self._communicate_with_poll(input)
+ else:
+ stdout, stderr = self._communicate_with_select(input)
+
+ # All data exchanged. Translate lists into strings.
+ if stdout is not None:
+ stdout = b''.join(stdout)
+ if stderr is not None:
+ stderr = b''.join(stderr)
+
+ # Translate newlines, if requested.
+ # This also turns bytes into strings.
+ if self.universal_newlines:
+ if stdout is not None:
+ stdout = self._translate_newlines(stdout,
+ self.stdout.encoding)
+ if stderr is not None:
+ stderr = self._translate_newlines(stderr,
+ self.stderr.encoding)
+
+ self.wait()
+ return (stdout, stderr)
+
+
+ def _communicate_with_poll(self, input):
+ stdout = None # Return
+ stderr = None # Return
+ fd2file = {}
+ fd2output = {}
+
+ poller = select.poll()
+ def register_and_append(file_obj, eventmask):
+ poller.register(file_obj.fileno(), eventmask)
+ fd2file[file_obj.fileno()] = file_obj
+
+ def close_unregister_and_remove(fd):
+ poller.unregister(fd)
+ fd2file[fd].close()
+ fd2file.pop(fd)
+
+ if self.stdin and input:
+ register_and_append(self.stdin, select.POLLOUT)
+
+ select_POLLIN_POLLPRI = select.POLLIN | select.POLLPRI
+ if self.stdout:
+ register_and_append(self.stdout, select_POLLIN_POLLPRI)
+ fd2output[self.stdout.fileno()] = stdout = []
+ if self.stderr:
+ register_and_append(self.stderr, select_POLLIN_POLLPRI)
+ fd2output[self.stderr.fileno()] = stderr = []
+
+ input_offset = 0
+ while fd2file:
+ try:
+ ready = poller.poll()
+ except select.error as e:
+ if e.args[0] == errno.EINTR:
+ continue
+ raise
+
+ # XXX Rewrite these to use non-blocking I/O on the
+ # file objects; they are no longer using C stdio!
+
+ for fd, mode in ready:
+ if mode & select.POLLOUT:
+ chunk = input[input_offset : input_offset + _PIPE_BUF]
+ input_offset += os.write(fd, chunk)
+ if input_offset >= len(input):
+ close_unregister_and_remove(fd)
+ elif mode & select_POLLIN_POLLPRI:
+ data = os.read(fd, 4096)
+ if not data:
+ close_unregister_and_remove(fd)
+ fd2output[fd].append(data)
+ else:
+ # Ignore hang up or errors.
+ close_unregister_and_remove(fd)
+
+ return (stdout, stderr)
+
+
+ def _communicate_with_select(self, input):
read_set = []
write_set = []
stdout = None # Return
stderr = None # Return
- if self.stdin:
- # Flush stdio buffer. This might block, if the user has
- # been writing to .stdin in an uncontrolled fashion.
- self.stdin.flush()
- if input:
- write_set.append(self.stdin)
- else:
- self.stdin.close()
+ if self.stdin and input:
+ write_set.append(self.stdin)
if self.stdout:
read_set.append(self.stdout)
stdout = []
@@ -1206,10 +1296,7 @@
# file objects; they are no longer using C stdio!
if self.stdin in wlist:
- # When select has indicated that the file is writable,
- # we can write up to PIPE_BUF bytes without risk
- # blocking. POSIX defines PIPE_BUF >= 512
- chunk = input[input_offset : input_offset + 512]
+ chunk = input[input_offset : input_offset + _PIPE_BUF]
bytes_written = os.write(self.stdin.fileno(), chunk)
input_offset += bytes_written
if input_offset >= len(input):
@@ -1230,25 +1317,9 @@
read_set.remove(self.stderr)
stderr.append(data)
- # All data exchanged. Translate lists into strings.
- if stdout is not None:
- stdout = b"".join(stdout)
- if stderr is not None:
- stderr = b"".join(stderr)
-
- # Translate newlines, if requested.
- # This also turns bytes into strings.
- if self.universal_newlines:
- if stdout is not None:
- stdout = self._translate_newlines(stdout,
- self.stdout.encoding)
- if stderr is not None:
- stderr = self._translate_newlines(stderr,
- self.stderr.encoding)
-
- self.wait()
return (stdout, stderr)
+
def send_signal(self, sig):
"""Send a signal to the process
"""