on 2014/01/10 22:10, shaohef@linux.vnet.ibm.com wrote:
From: ShaoHe Feng <shaohef@linux.vnet.ibm.com>
We need a common function to execute shell command. We also need timeout when execute shell command.
A threading.Timer is used to send signal.SIGKILL to kill the command when timeout.
Signed-off-by: Royce Lv <lvroyce@linux.vnet.ibm.com> Signed-off-by: ShaoHe Feng <shaohef@linux.vnet.ibm.com> --- src/kimchi/utils.py | 43 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 43 insertions(+)
diff --git a/src/kimchi/utils.py b/src/kimchi/utils.py index af245c6..c7165ce 100644 --- a/src/kimchi/utils.py +++ b/src/kimchi/utils.py @@ -23,6 +23,7 @@
import cherrypy import os +import subprocess import urllib2
@@ -30,6 +31,7 @@ from cherrypy.lib.reprconf import Parser
from kimchi import config +from threading import Timer
kimchi_log = cherrypy.log.error_log @@ -96,3 +98,44 @@ def check_url_path(path): return False
return True + + +def run_command(cmd, timeout=None):
I think it will be useful if you can add a docstring here explaining that timeout is a float number in seconds.
+ def kill_proc(proc, timeout_flag): + timeout_flag[0] = True + proc.kill() +
Though it's rare, but I think it's still possible that the sub-process exits before the timeout, but the timer expires just before we execute the timer.cancel(). There is always a small time window between "communicate()" and "cancel()". It's possible that Python switches context to the timer thread during this time window, and it would except "OSError: [Errno 3] No such process" here. I think it's better to except OSError and swallow the exception. Which means the following. def kill_proc(proc, timeout_flag): try: proc.kill() except OSError: pass else: timeout_flag[0] = True
+ proc = None + timer = None + timeout_flag = [False] + + try: + proc = subprocess.Popen(cmd, stdout=subprocess.PIPE, + stderr=subprocess.PIPE) + if timeout is not None: + timer = Timer(timeout, kill_proc, [proc, timeout_flag])
As far as I test, timer threads do not automatically set the .daemon attribute to True. The .daemon of a thread is False by default [1], and it prevents the process from exiting. I think we should set .daemon to True for timer threads, and they get killed if the process is stopping. [1] http://docs.python.org/2/library/threading.html#thread-objects
+ timer.start() + + out, error = proc.communicate() + kimchi_log.debug("Run command: '%s'", " ".join(cmd)) + + if out or error: + kimchi_log.debug("out:\n %s\nerror:\n %s", out, error) + + if proc.returncode == -9 and timeout_flag[0] is True:
I think you can safely drop "is True", just "if ... and timeout_flag[0]" is also correct and shorter. If you applied my suggestions excepting and swallowing OSError in kill_proc(), you might also be able to drop the "returncode == -9". In all, I think it may be simplified as the following. if timeout_flag[0]: kimchi_log.error("subprocess executed timeout for %s seconds, " "return code %s" % (timeout, proc.returncode))
+ kimchi_log.error("subprocess is killed by signal.SIGKILL " + "for timeout %s seconds", timeout) + + return out, error, proc.returncode, timeout_flag[0] + except Exception as e: + msg = "Failed to run command: %s." % " ".join(cmd) + msg = msg if proc is None else msg + "\n error code: %s." + kimchi_log.error("%s\n %s", msg, e) + + if proc: + return out, error, proc.returncode, timeout_flag[0] + else: + return None, None, None, timeout_flag[0] + finally: + if timer and not timeout_flag[0]: + timer.cancel()
-- Thanks and best regards! Zhou Zheng Sheng / 周征晟 E-mail: zhshzhou@linux.vnet.ibm.com Telephone: 86-10-82454397