From b4e9dc3ab96e699a38a71aa6bb46337a596312d5 Mon Sep 17 00:00:00 2001
From: John Morrissey <jwm@horde.net>
Date: Fri, 12 Dec 2014 13:23:25 -0500
Subject: read in >1 byte chunks, and set a useful timeout on select()

this way, we're not rolling this loop over nearly as much, while still
preserving the overall timeout semantics
---
 paramiko/proxy.py | 19 ++++++++++++-------
 1 file changed, 12 insertions(+), 7 deletions(-)

diff --git a/paramiko/proxy.py b/paramiko/proxy.py
index 8959b244..25666be5 100644
--- a/paramiko/proxy.py
+++ b/paramiko/proxy.py
@@ -24,6 +24,7 @@ import signal
 from subprocess import Popen, PIPE
 from select import select
 import socket
+import time
 
 from paramiko.ssh_exception import ProxyCommandFailure
 
@@ -76,20 +77,24 @@ class ProxyCommand(object):
         :return: the length of the read content, as an `int`
         """
         try:
-            start = datetime.now()
+            start = time.time()
             while len(self.buffer) < size:
+                select_timeout = None
                 if self.timeout is not None:
-                    elapsed = (datetime.now() - start).microseconds
-                    timeout = self.timeout * 1000 * 1000  # to microseconds
-                    if elapsed >= timeout:
+                    elapsed = (time.time() - start)
+                    if elapsed >= self.timeout:
                         raise socket.timeout()
-                r, w, x = select([self.process.stdout], [], [], 0.0)
+                    select_timeout = self.timeout - elapsed
+
+                r, w, x = select(
+                    [self.process.stdout], [], [], select_timeout)
                 if r and r[0] == self.process.stdout:
-                    b = os.read(self.process.stdout.fileno(), 1)
+                    b = os.read(
+                        self.process.stdout.fileno(), size - len(self.buffer))
                     # Store in class-level buffer for persistence across
                     # timeouts; this makes us act more like a real socket
                     # (where timeouts don't actually drop data.)
-                    self.buffer.append(b)
+                    self.buffer.extend(b)
             result = ''.join(self.buffer)
             self.buffer = []
             return result
-- 
cgit v1.2.3


From 741b4fbb9322a45282e86958c92b1b6706c07f8c Mon Sep 17 00:00:00 2001
From: Jeff Forcier <jeff@bitprophet.org>
Date: Thu, 18 Dec 2014 13:53:24 -0800
Subject: Changelog re #413, closes #454

---
 sites/www/changelog.rst | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/sites/www/changelog.rst b/sites/www/changelog.rst
index 99c28fbd..66bbb806 100644
--- a/sites/www/changelog.rst
+++ b/sites/www/changelog.rst
@@ -2,6 +2,11 @@
 Changelog
 =========
 
+* :bug:`413` (also :issue:`414`, :issue:`420`, :issue:`454`) Be significantly
+  smarter about polling & timing behavior when running proxy commands, to avoid
+  unnecessary (often 100%!) CPU usage. Major thanks to Jason Dunsmore for
+  report & initial patchset and to Chris Adams & John Morrissey for followup
+  improvements.
 * :bug:`428` Fix an issue in `~paramiko.file.BufferedFile` (primarily used in
   the SFTP modules) concerning incorrect behavior by
   `~paramiko.file.BufferedFile.readlines` on files whose size exceeds the
-- 
cgit v1.2.3