Question

我正在仔细阅读此处发布的问题：

What should I do if socket.setdefaulttimeout() is not working?

尝试在mechanize.Browser对象花费太长时间时提出解决方案来杀死请求，并且我一直在尝试使用tomasz编辑中的第一个解决方案（为了清晰起见，这里重新发布）：

import signal, time

def request(arg):
  """Your http request"""
  time.sleep(2)
  return arg

class Timeout():
  """Timeout class using ALARM signal"""
  class Timeout(Exception): pass

  def __init__(self, sec):
    self.sec = sec

  def __enter__(self):
    signal.signal(signal.SIGALRM, self.raise_timeout)
    signal.alarm(self.sec)

  def __exit__(self, *args):
    signal.alarm(0) # disable alarm

  def raise_timeout(self, *args):
    raise Timeout.Timeout()

# Run block of code with timeouts
try:
  with Timeout(3):
    print request("Request 1")
  with Timeout(1):
    print request("Request 2")
except Timeout.Timeout:
  print "Timeout"

# Prints "Request 1" and "Timeout"

当我使用python timeout.py从我的终端运行此版本（版本为Python 2.7.2+而我在Ubuntu 11.10 Oneiric Ocelot上）时，没有抛出任何异常 - 而只是打印

Request 1
Request 2

有人可以解释一下如何解决这个问题吗？有关signal.alarm和signal.signal次调用的内容的解释也很棒。

非常感谢你的时间！

编辑：

运行strace -f python timeout.py会产生：

alarm(3)                                = 0
select(0, NULL, NULL, NULL, {2, 0})     = 0 (Timeout)
fstat64(1, {st_mode=S_IFREG|0664, st_size=0, ...}) = 0
mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xb740c000
alarm(0)                                = 1
rt_sigaction(SIGALRM, {0x812f450, [], 0}, {0x812f450, [], 0}, 8) = 0
alarm(1)                                = 0
select(0, NULL, NULL, NULL, {2, 0})     = 0 (Timeout)
alarm(0)                                = 0
rt_sigaction(SIGINT, {SIG_DFL, [], 0}, {0x812f450, [], 0}, 8) = 0
rt_sigaction(SIGALRM, {SIG_DFL, [], 0}, {0x812f450, [], 0}, 8) = 0
write(1, "Request 1\nRequest 2\n", 20)  = 20
exit_group(0)                           = ?

Answer 1

如果你想知道这里发生了什么，请尝试：

$ strace -f python timeout.py

对我来说（使用python 2.6运行Debian 6）这是有效的。 strace输出的重要部分：

alarm(3)                                = 0
select(0, NULL, NULL, NULL, {2, 0})     = 0 (Timeout)
fstat(1, {st_mode=S_IFCHR|0620, st_rdev=makedev(136, 15), ...}) = 0
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) =  x7f0fbbe06000
write(1, "Request 1\n", 10Request 1)             = 10
alarm(0)                                = 1
rt_sigaction(SIGALRM, {0x4d0a90, [], SA_RESTORER, 0x7f0fbb9deff0}, {0x4d0a90, [], SA_RESTORER, 0x7f0fbb9deff0}, 8) = 0
alarm(1)                                = 0
select(0, NULL, NULL, NULL, {2, 0})     = ? ERESTARTNOHAND (To be restarted)
--- SIGALRM (Alarm clock) @ 0 (0) ---
rt_sigreturn(0xffffffff)                = -1 EINTR (Interrupted system call)
alarm(0)                                = 0
write(1, "Timeout\n", 8Timeout
)                = 8

报警（3）被调用;请求1通过;调用alarm（1），给出超时。

为mechanize.Browser设置超时

1 个答案: