我正在编写一个连接X个UNIX套接字的工具，发送命令并将输出保存在本地文件系统中。它每X秒运行一次。为了在工具接收终止信号时执行一些清理，我将一个函数（关闭）注册到signal.SIGHUP和signal.SIGTERM信号。此函数取消所有任务，然后关闭事件循环。
我的问题是我得到了
RuntimeError：事件循环在未完成之前停止
当我发送signal.SIGTERM（kill'pid'）。我已经阅读了两次取消任务的文档，但我没有发现我在这里做错了什么。
我也注意到一些奇怪的事情，当我发送终止信号时，程序处于睡眠模式，我在日志中看到它唤醒了pull_stats（）协程，你可以在日志的前两行看到这一点。
日志：
21:53:44,194 [23031] [MainThread:supervisor ] DEBUG **sleeping for 9.805s secs**
21:53:45,857 [23031] [MainThread:pull_stats ] INFO pull statistics
21:53:45,858 [23031] [MainThread:get ] DEBUG connecting to UNIX socket /run/haproxy/admin1.sock
21:53:45,858 [23031] [MainThread:get ] DEBUG connecting to UNIX socket /run/haproxy/admin4.sock
21:53:45,858 [23031] [MainThread:get ] DEBUG connecting to UNIX socket /run/haproxy/admin3.sock
21:53:45,858 [23031] [MainThread:get ] DEBUG connecting to UNIX socket /run/haproxy/admin3.sock
21:53:45,858 [23031] [MainThread:get ] DEBUG connecting to UNIX socket /run/haproxy/admin2.sock
21:53:45,858 [23031] [MainThread:get ] DEBUG connecting to UNIX socket /run/haproxy/admin2.sock
21:53:45,858 [23031] [MainThread:get ] DEBUG connecting to UNIX socket /run/haproxy/admin4.sock
21:53:45,859 [23031] [MainThread:get ] DEBUG connecting to UNIX socket /run/haproxy/admin1.sock
21:53:45,859 [23031] [MainThread:shutdown ] INFO received stop signal, cancelling tasks...
21:53:45,859 [23031] [MainThread:shutdown ] INFO True
21:53:45,859 [23031] [MainThread:shutdown ] INFO True
21:53:45,859 [23031] [MainThread:shutdown ] INFO True
21:53:45,859 [23031] [MainThread:shutdown ] INFO True
21:53:45,859 [23031] [MainThread:shutdown ] INFO True
21:53:45,859 [23031] [MainThread:shutdown ] INFO True
21:53:45,859 [23031] [MainThread:shutdown ] INFO True
21:53:45,859 [23031] [MainThread:shutdown ] INFO True
21:53:45,859 [23031] [MainThread:shutdown ] INFO True
21:53:45,859 [23031] [MainThread:shutdown ] INFO True
21:53:45,859 [23031] [MainThread:shutdown ] INFO True
21:53:45,859 [23031] [MainThread:shutdown ] INFO True
21:53:45,859 [23031] [MainThread:shutdown ] INFO True
21:53:45,859 [23031] [MainThread:shutdown ] INFO True
21:53:45,859 [23031] [MainThread:shutdown ] INFO True
21:53:45,859 [23031] [MainThread:shutdown ] INFO True
21:53:45,860 [23031] [MainThread:shutdown ] INFO True
21:53:45,860 [23031] [MainThread:shutdown ] INFO stopping event loop
21:53:45,860 [23031] [MainThread:shutdown ] INFO bye, exiting...
Traceback (most recent call last):
File "./pull.py", line 249, in <module>
main()
File "./pull.py", line 245, in main
supervisor(loop, config)
File "./pull.py", line 161, in supervisor
config['pull']['socket-dir'], storage_dir, loop))
File "/usr/lib/python3.4/asyncio/base_events.py", line 274, in run_until_complete
raise RuntimeError('Event loop stopped before Future completed.')
RuntimeError: Event loop stopped before Future completed.
以下是代码：
def shutdown(loop):
LOGGER.info('received stop signal, cancelling tasks...')
for task in asyncio.Task.all_tasks():
LOGGER.info(task.cancel())
LOGGER.info('stopping event loop')
loop.stop()
LOGGER.info('bye, exiting...')
def write_file(filename, data):
try:
with open(filename, 'w') as file_handle:
file_handle.write(data.decode())
except OSError as exc:
return False
else:
return True
@asyncio.coroutine
def get(socket_file, cmd, storage_dir, loop):
connect = asyncio.open_unix_connection(socket_file)
reader, writer = yield from asyncio.wait_for(connect, 1)
writer.write('{c}\n'.format(c=cmd).encode())
data = yield from reader.read()
writer.close()
filename = os.path.basename(socket_file) + '_' + cmd.split()[1]
filename = os.path.join(storage_dir, filename)
result = yield from loop.run_in_executor(None, write_file, filename, data)
return result
@asyncio.coroutine
def pull_stats(socket_dir, storage_dir, loop):
socket_files = glob.glob(socket_dir + '/*sock*')
coroutines = [get(socket_file, cmd, storage_dir, loop)
for socket_file in socket_files
for cmd in CMDS]
status = yield from asyncio.gather(*coroutines)
if len(set(status)) == 1 and True in set(status):
return True
else:
return False
def supervisor(loop, config):
dst_dir = config.get('pull', 'dst-dir')
tmp_dst_dir = config.get('pull', 'tmp-dst-dir')
while True:
start_time = int(time.time())
storage_dir = os.path.join(tmp_dst_dir, str(start_time))
try:
os.makedirs(storage_dir)
except OSError as exc:
msg = "failed to create directory {d}:{e}".format(d=storage_dir,
e=exc)
LOGGER.critical(msg)
# Launch all connections.
result = loop.run_until_complete(pull_stats(
config['pull']['socket-dir'], storage_dir, loop))
if result:
try:
shutil.move(storage_dir, dst_dir)
except OSError as exc:
LOGGER.critical("failed to move %s to %s: %s", storage_dir,
dst_dir, exc)
break
else:
LOGGER.info('statistics are saved in %s', os.path.join(
dst_dir, os.path.basename(storage_dir)))
else:
LOGGER.critical('failed to pull stats')
shutil.rmtree(storage_dir)
sleep = config.getint('pull', 'pull-interval') - (time.time() -
start_time)
if 0 < sleep < config.getint('pull', 'pull-interval'):
time.sleep(sleep)
loop.close()
sys.exit(1)
def main():
args = docopt(__doc__, version=VERSION)
config = ConfigParser(interpolation=ExtendedInterpolation())
config.read_dict(copy.copy(DEFAULT_OPTIONS))
config.read(args['--file'])
loop = asyncio.get_event_loop()
loop.add_signal_handler(signal.SIGHUP, functools.partial(shutdown, loop))
loop.add_signal_handler(signal.SIGTERM, functools.partial(shutdown, loop))
num_level = getattr(logging, config.get('pull', 'loglevel').upper(), None)
LOGGER.setLevel(num_level)
supervisor(loop, config)
# This is the standard boilerplate that calls the main() function.
if __name__ == '__main__':
main()
答案 0 :(得分：11)
取消不是立即取消，需要运行ioloop才能解决异常CancelledError。从关机中删除ioloop.stop并在主管中处理异常，以使工作正常。下面简化的例子。
重要的是，你可以取消Task，它只会停止观看/等待结束/结果，而循环不会处理它的进一步事件。但是下面的请求/管道不会被停止。
简化示例：
import asyncio
import functools
import logging
import signal
import sys
from concurrent.futures import CancelledError
def shutdown(loop):
logging.info('received stop signal, cancelling tasks...')
for task in asyncio.Task.all_tasks():
task.cancel()
logging.info('bye, exiting in a minute...')
@asyncio.coroutine
def get(i):
logging.info('sleep for %d', i)
yield from asyncio.sleep(i)
@asyncio.coroutine
def pull_stats():
coroutines = [get(i) for i in range(10,20)]
status = yield from asyncio.gather(*coroutines)
def supervisor(loop):
try:
while True:
result = loop.run_until_complete(pull_stats())
except CancelledError:
logging.info('CancelledError')
loop.close()
sys.exit(1)
def main():
logging.getLogger().setLevel(logging.INFO)
loop = asyncio.get_event_loop()
loop.add_signal_handler(signal.SIGHUP, functools.partial(shutdown, loop))
loop.add_signal_handler(signal.SIGTERM, functools.partial(shutdown, loop))
supervisor(loop)
if __name__ == '__main__':
main()
请注意，如果您仅取消gather's未来，则所有孩子也将被取消。
睡觉之物
任何信号或中断的接收都会导致程序恢复执行。因此，当进程接收SIGTERM并设置处理程序时，python允许您处理它，执行此线程恢复并调用sighandler。由于ioloop的实现及其信号处理，它在唤醒后继续运行。
答案 1 :(得分：0)
更新：代码在python 3.4.4上按预期工作，请参阅下面的评论。 @kwarunek，当你提到你关于ioloop的最后一条评论一直在运行时，由于我的代码工作，我没有完全得到它，查杀过程会对所有醒来的任务发送取消。但是，现在我看到了你的观点，因为取消任务不是用3.4.4触发的，3.4.2就好了。
21:28:09,004 [59441] [MainThread:supervisor] CRITICAL failed to pull stats
<killing process>
21:28:11,826 [59441] [MainThread:supervisor] INFO starting while loop
21:28:11,827 [59441] [MainThread:supervisor] INFO launch the delegating coroutine
21:28:11,828 [59441] [MainThread:shutdown] INFO received stop signal
21:28:11,828 [59441] [MainThread:shutdown] INFO <Task finished coro=<pull_stats() done, defined at /opt/blue-python/3.4/lib/python3.4/site-packages/haproxystats/pull.py:124> result=False>
21:28:11,829 [59441] [MainThread:shutdown] INFO cancelling task
21:28:11,829 [59441] [MainThread:supervisor] INFO delegating coroutine finished
21:28:11,829 [59441] [MainThread:supervisor] CRITICAL failed to pull stats
21:28:21,009 [59441] [MainThread:supervisor] INFO starting while loop
21:28:21,010 [59441] [MainThread:supervisor] INFO launch the delegating coroutine
21:28:21,011 [59441] [MainThread:supervisor] INFO delegating coroutine finished
2016-01-30 21:28:21,011 [59441] [MainThread:supervisor] CRITICAL failed to pull stats
在python 3.4.2中
21:23:51,015 [10219] [MainThread:supervisor] CRITICAL failed to pull stats
<killing process>
21:23:55,737 [10219] [MainThread:supervisor] INFO starting while loop
21:23:55,737 [10219] [MainThread:supervisor] INFO launch the delegating coroutine
21:23:55,740 [10219] [MainThread:shutdown] INFO received stop signal
21:23:55,740 [10219] [MainThread:shutdown] INFO <Task finished coro=<open_unix_connection() done, defined at /usr/lib/python3.4/asyncio/streams.py:107> exception=ConnectionRefusedError(111, 'Connection refused')>
21:23:55,740 [10219] [MainThread:shutdown] INFO cancelling task
21:23:55,740 [10219] [MainThread:shutdown] INFO <Task finished coro=<open_unix_connection() done, defined at /usr/lib/python3.4/asyncio/streams.py:107> exception=ConnectionRefusedError(111, 'Connection refused')>
21:23:55,741 [10219] [MainThread:shutdown] INFO cancelling task
21:23:55,741 [10219] [MainThread:shutdown] INFO <Task finished coro=<open_unix_connection() done, defined at /usr/lib/python3.4/asyncio/streams.py:107> exception=ConnectionRefusedError(111, 'Connection refused')>
21:23:55,741 [10219] [MainThread:shutdown] INFO cancelling task
21:23:55,741 [10219] [MainThread:shutdown] INFO <Task finished coro=<open_unix_connection() done, defined at /usr/lib/python3.4/asyncio/streams.py:107> exception=ConnectionRefusedError(111, 'Connection refused')>
21:23:55,741 [10219] [MainThread:shutdown] INFO cancelling task
21:23:55,741 [10219] [MainThread:shutdown] INFO <Task finished coro=<open_unix_connection() done, defined at /usr/lib/python3.4/asyncio/streams.py:107> exception=ConnectionRefusedError(111, 'Connection refused')>
21:23:55,741 [10219] [MainThread:shutdown] INFO cancelling task
21:23:55,742 [10219] [MainThread:shutdown] INFO <Task finished coro=<open_unix_connection() done, defined at /usr/lib/python3.4/asyncio/streams.py:107> exception=ConnectionRefusedError(111, 'Connection refused')>
21:23:55,742 [10219] [MainThread:shutdown] INFO cancelling task
21:23:55,742 [10219] [MainThread:shutdown] INFO <Task finished coro=<open_unix_connection() done, defined at /usr/lib/python3.4/asyncio/streams.py:107> exception=ConnectionRefusedError(111, 'Connection refused')>
21:23:55,742 [10219] [MainThread:shutdown] INFO cancelling task
21:23:55,742 [10219] [MainThread:shutdown] INFO <Task finished coro=<open_unix_connection() done, defined at /usr/lib/python3.4/asyncio/streams.py:107> exception=ConnectionRefusedError(111, 'Connection refused')>
21:23:55,742 [10219] [MainThread:shutdown] INFO cancelling task
21:23:55,742 [10219] [MainThread:shutdown] INFO <Task finished coro=<pull_stats() done, defined at /home/pparissis/.virtualenvs/python3/lib/python3.4/site-packages/haproxystats/pull.py:124> result=False>
21:23:55,743 [10219] [MainThread:shutdown] INFO cancelling task
21:23:55,743 [10219] [MainThread:shutdown] INFO <Task pending coro=<get() running at /home/pparissis/.virtualenvs/python3/lib/python3.4/site-packages/haproxystats/pull.py:93> wait_for=<Future pending cb=[Task._wakeup()]> cb=[gather.<locals>._done_callback(0)() at /usr/lib/python3.4/asyncio/tasks.py:582]>
21:23:55,743 [10219] [MainThread:shutdown] INFO cancelling task
21:23:55,743 [10219] [MainThread:shutdown] INFO <Task finished coro=<pull_stats() done, defined at /home/pparissis/.virtualenvs/python3/lib/python3.4/site-packages/haproxystats/pull.py:124> result=False>
21:23:55,744 [10219] [MainThread:shutdown] INFO cancelling task
21:23:55,744 [10219] [MainThread:shutdown] INFO <Task pending coro=<get() running at /home/pparissis/.virtualenvs/python3/lib/python3.4/site-packages/haproxystats/pull.py:93> wait_for=<Future pending cb=[Task._wakeup()]> cb=[gather.<locals>._done_callback(7)() at /usr/lib/python3.4/asyncio/tasks.py:582]>
21:23:55,744 [10219] [MainThread:shutdown] INFO cancelling task
21:23:55,744 [10219] [MainThread:shutdown] INFO <Task pending coro=<get() running at /home/pparissis/.virtualenvs/python3/lib/python3.4/site-packages/haproxystats/pull.py:93> wait_for=<Future pending cb=[Task._wakeup()]> cb=[gather.<locals>._done_callback(4)() at /usr/lib/python3.4/asyncio/tasks.py:582]>
21:23:55,745 [10219] [MainThread:shutdown] INFO cancelling task
21:23:55,745 [10219] [MainThread:shutdown] INFO <Task pending coro=<get() running at /home/pparissis/.virtualenvs/python3/lib/python3.4/site-packages/haproxystats/pull.py:93> wait_for=<Future pending cb=[Task._wakeup()]> cb=[gather.<locals>._done_callback(5)() at /usr/lib/python3.4/asyncio/tasks.py:582]>
21:23:55,745 [10219] [MainThread:shutdown] INFO cancelling task
21:23:55,745 [10219] [MainThread:shutdown] INFO <Task pending coro=<open_unix_connection() running at /usr/lib/python3.4/asyncio/streams.py:107> cb=[_release_waiter(<Future pendi...sk._wakeup()]>)() at /usr/lib/python3.4/asyncio/tasks.py:334]>
21:23:55,746 [10219] [MainThread:shutdown] INFO cancelling task
21:23:55,746 [10219] [MainThread:shutdown] INFO <Task pending coro=<get() running at /home/pparissis/.virtualenvs/python3/lib/python3.4/site-packages/haproxystats/pull.py:93> wait_for=<Future pending cb=[Task._wakeup()]> cb=[gather.<locals>._done_callback(3)() at /usr/lib/python3.4/asyncio/tasks.py:582]>
21:23:55,746 [10219] [MainThread:shutdown] INFO cancelling task
21:23:55,746 [10219] [MainThread:shutdown] INFO <Task pending coro=<open_unix_connection() running at /usr/lib/python3.4/asyncio/streams.py:107> cb=[_release_waiter(<Future pendi...sk._wakeup()]>)() at /usr/lib/python3.4/asyncio/tasks.py:334]>
21:23:55,747 [10219] [MainThread:shutdown] INFO cancelling task
21:23:55,747 [10219] [MainThread:shutdown] INFO <Task pending coro=<get() running at /home/pparissis/.virtualenvs/python3/lib/python3.4/site-packages/haproxystats/pull.py:93> wait_for=<Future pending cb=[Task._wakeup()]> cb=[gather.<locals>._done_callback(6)() at /usr/lib/python3.4/asyncio/tasks.py:582]>
21:23:55,747 [10219] [MainThread:shutdown] INFO cancelling task
21:23:55,747 [10219] [MainThread:shutdown] INFO <Task pending coro=<open_unix_connection() running at /usr/lib/python3.4/asyncio/streams.py:107> cb=[_release_waiter(<Future pendi...sk._wakeup()]>)() at /usr/lib/python3.4/asyncio/tasks.py:334]>
21:23:55,747 [10219] [MainThread:shutdown] INFO cancelling task
21:23:55,747 [10219] [MainThread:shutdown] INFO <Task pending coro=<pull_stats() running at /home/pparissis/.virtualenvs/python3/lib/python3.4/site-packages/haproxystats/pull.py:150> wait_for=<_GatheringFuture pending cb=[Task._wakeup()]> cb=[_raise_stop_error() at /usr/lib/python3.4/asyncio/base_events.py:101]>
21:23:55,748 [10219] [MainThread:shutdown] INFO cancelling task
21:23:55,748 [10219] [MainThread:shutdown] INFO <Task pending coro=<get() running at /home/pparissis/.virtualenvs/python3/lib/python3.4/site-packages/haproxystats/pull.py:93> wait_for=<Future cancelled> cb=[gather.<locals>._done_callback(2)() at /usr/lib/python3.4/asyncio/tasks.py:582]>
21:23:55,748 [10219] [MainThread:shutdown] INFO cancelling task
21:23:55,748 [10219] [MainThread:shutdown] INFO <Task pending coro=<open_unix_connection() running at /usr/lib/python3.4/asyncio/streams.py:107> cb=[_release_waiter(<Future cancelled>)() at /usr/lib/python3.4/asyncio/tasks.py:334]>
21:23:55,748 [10219] [MainThread:shutdown] INFO cancelling task
21:23:55,749 [10219] [MainThread:shutdown] INFO <Task finished coro=<open_unix_connection() done, defined at /usr/lib/python3.4/asyncio/streams.py:107> exception=ConnectionRefusedError(111, 'Connection refused')>
21:23:55,749 [10219] [MainThread:shutdown] INFO cancelling task
21:23:55,749 [10219] [MainThread:shutdown] INFO <Task finished coro=<open_unix_connection() done, defined at /usr/lib/python3.4/asyncio/streams.py:107> exception=ConnectionRefusedError(111, 'Connection refused')>
21:23:55,749 [10219] [MainThread:shutdown] INFO cancelling task
21:23:55,749 [10219] [MainThread:shutdown] INFO <Task pending coro=<open_unix_connection() running at /usr/lib/python3.4/asyncio/streams.py:107> cb=[_release_waiter(<Future cancelled>)() at /usr/lib/python3.4/asyncio/tasks.py:334]>
21:23:55,750 [10219] [MainThread:shutdown] INFO cancelling task
21:23:55,750 [10219] [MainThread:shutdown] INFO <Task finished coro=<open_unix_connection() done, defined at /usr/lib/python3.4/asyncio/streams.py:107> exception=ConnectionRefusedError(111, 'Connection refused')>
21:23:55,750 [10219] [MainThread:shutdown] INFO cancelling task
21:23:55,750 [10219] [MainThread:shutdown] INFO <Task finished coro=<open_unix_connection() done, defined at /usr/lib/python3.4/asyncio/streams.py:107> exception=ConnectionRefusedError(111, 'Connection refused')>
21:23:55,750 [10219] [MainThread:shutdown] INFO cancelling task
21:23:55,751 [10219] [MainThread:shutdown] INFO <Task pending coro=<open_unix_connection() running at /usr/lib/python3.4/asyncio/streams.py:107> cb=[_release_waiter(<Future cancelled>)() at /usr/lib/python3.4/asyncio/tasks.py:334]>
21:23:55,751 [10219] [MainThread:shutdown] INFO cancelling task
21:23:55,751 [10219] [MainThread:shutdown] INFO <Task finished coro=<open_unix_connection() done, defined at /usr/lib/python3.4/asyncio/streams.py:107> exception=ConnectionRefusedError(111, 'Connection refused')>
21:23:55,751 [10219] [MainThread:shutdown] INFO cancelling task
21:23:55,751 [10219] [MainThread:shutdown] INFO <Task finished coro=<open_unix_connection() done, defined at /usr/lib/python3.4/asyncio/streams.py:107> exception=ConnectionRefusedError(111, 'Connection refused')>
21:23:55,751 [10219] [MainThread:shutdown] INFO cancelling task
21:23:55,752 [10219] [MainThread:shutdown] INFO <Task pending coro=<open_unix_connection() running at /usr/lib/python3.4/asyncio/streams.py:107> cb=[_release_waiter(<Future cancelled>)() at /usr/lib/python3.4/asyncio/tasks.py:334]>
21:23:55,752 [10219] [MainThread:shutdown] INFO cancelling task
21:23:55,752 [10219] [MainThread:shutdown] INFO <Task finished coro=<open_unix_connection() done, defined at /usr/lib/python3.4/asyncio/streams.py:107> exception=ConnectionRefusedError(111, 'Connection refused')>
21:23:55,752 [10219] [MainThread:shutdown] INFO cancelling task
21:23:55,752 [10219] [MainThread:shutdown] INFO <Task finished coro=<open_unix_connection() done, defined at /usr/lib/python3.4/asyncio/streams.py:107> exception=ConnectionRefusedError(111, 'Connection refused')>
21:23:55,752 [10219] [MainThread:shutdown] INFO cancelling task
21:23:55,752 [10219] [MainThread:shutdown] INFO <Task pending coro=<get() running at /home/pparissis/.virtualenvs/python3/lib/python3.4/site-packages/haproxystats/pull.py:93> wait_for=<Future cancelled> cb=[gather.<locals>._done_callback(1)() at /usr/lib/python3.4/asyncio/tasks.py:582]>
21:23:55,753 [10219] [MainThread:shutdown] INFO cancelling task
21:23:55,753 [10219] [MainThread:shutdown] INFO <Task pending coro=<open_unix_connection() running at /usr/lib/python3.4/asyncio/streams.py:107> cb=[_release_waiter(<Future cancelled>)() at /usr/lib/python3.4/asyncio/tasks.py:334]>
21:23:55,753 [10219] [MainThread:shutdown] INFO cancelling task
21:23:55,754 [10219] [MainThread:supervisor] INFO Received CancelledError exception
21:23:55,754 [10219] [MainThread:supervisor] INFO waiting for threads to finish any pending IO tasks
21:23:55,754 [10219] [MainThread:supervisor] INFO closing our asyncio loop
21:23:55,755 [10219] [MainThread:supervisor] INFO exiting with status 0
主要区别在于shutdown（）发送取消时没有任务被唤醒，因此while循环不会被处理取消的try catch块停止。我现在如何解决这个问题？！
这是代码
def shutdown():
"""Performs a clean shutdown"""
log.info('received stop signal')
for task in asyncio.Task.all_tasks():
log.info(task)
log.info('cancelling task')
task.cancel()
def write_file(filename, data):
"""Writes data to a file.
Returns:
True if succeeds False otherwise.
"""
try:
with open(filename, 'w') as file_handle:
file_handle.write(data.decode())
except OSError as exc:
log.critical('failed to write data %s', exc)
return False
else:
log.debug('data saved in %s', filename)
return True
@asyncio.coroutine
def get(socket_file, cmd, storage_dir, loop, executor, timeout):
"""Fetches data from a UNIX socket.
Sends a command to HAProxy over UNIX socket, reads the response and then
offloads the writing of the received data to a thread, so we don't block
this coroutine.
Arguments:
socket_file (str): The full path of the UNIX socket file to connect to.
cmd (str): The command to send.
storage_dir (str): The full path of the directory to save the response.
loop (obj): A base event loop from asyncio module.
executor (obj): A Threader executor to execute calls asynchronously.
timeout (int): Timeout for the connection to the socket.
Returns:
True if statistics from a UNIX sockets are save False otherwise.
"""
# try to connect to the UNIX socket
connect = asyncio.open_unix_connection(socket_file)
log.debug('connecting to UNIX socket %s', socket_file)
try:
reader, writer = yield from asyncio.wait_for(connect, timeout)
except (ConnectionRefusedError, PermissionError, OSError) as exc:
log.critical(exc)
return False
else:
log.debug('connection established to UNIX socket %s', socket_file)
log.debug('sending command "%s" to UNIX socket %s', cmd, socket_file)
writer.write('{c}\n'.format(c=cmd).encode())
data = yield from reader.read()
writer.close()
if len(data) == 0:
log.critical('received zero data')
return False
log.debug('received data from UNIX socket %s', socket_file)
suffix = CMD_SUFFIX_MAP.get(cmd.split()[1])
filename = os.path.basename(socket_file) + suffix
filename = os.path.join(storage_dir, filename)
log.debug('going to save data to %s', filename)
# Offload the writing to a thread so we don't block ourselves.
result = yield from loop.run_in_executor(executor,
write_file,
filename,
data)
return result
@asyncio.coroutine
def pull_stats(config, storage_dir, loop, executor):
"""Launches coroutines for pulling statistics from UNIX sockets.
This a delegating routine.
Arguments:
config (obj): A configParser object which holds configuration.
storage_dir (str): The absolute directory path to save the statistics.
loop (obj): A base event loop.
executor(obj): A ThreadPoolExecutor object.
Returns:
True if statistics from *all* UNIX sockets are fetched False otherwise.
"""
# absolute directory path which contains UNIX socket files.
socket_dir = config.get('pull', 'socket-dir')
timeout = config.getint('pull', 'timeout')
socket_files = [f for f in glob.glob(socket_dir + '/*')
if is_unix_socket(f)]
log.debug('pull statistics')
coroutines = [get(socket_file, cmd, storage_dir, loop, executor, timeout)
for socket_file in socket_files
for cmd in CMDS]
# Launch all connections.
status = yield from asyncio.gather(*coroutines)
return len(set(status)) == 1 and True in set(status)
def supervisor(loop, config):
"""Coordinates the pulling of HAProxy statistics from UNIX sockets.
This is the client routine which launches requests to all HAProxy
UNIX sockets for retrieving statistics and save them to file-system.
It runs indefinitely until main program is terminated.
Arguments:
loop (obj): A base event loop from asyncio module.
config (obj): A configParser object which holds configuration.
"""
dst_dir = config.get('pull', 'dst-dir')
tmp_dst_dir = config.get('pull', 'tmp-dst-dir')
executor = ThreadPoolExecutor(max_workers=config.getint('pull', 'workers'))
exit_code = 1
while True:
log.info('starting while loop')
start_time = int(time.time())
# HAProxy statistics are stored in a directory and we use retrieval
# time(seconds since the Epoch) as a name of the directory.
# We first store them in a temporary place until we receive statistics
# from all UNIX sockets.
storage_dir = os.path.join(tmp_dst_dir, str(start_time))
# If our storage directory can't be created we can't do much, thus
# abort main program.
try:
os.makedirs(storage_dir)
except OSError as exc:
msg = "failed to make directory {d}:{e}".format(d=storage_dir,
e=exc)
log.critical(msg)
log.critical('a fatal error has occurred, exiting..')
break
try:
log.info('launch the delegating coroutine')
result = loop.run_until_complete(pull_stats(config, storage_dir,
loop, executor))
log.info('delegating coroutine finished')
except asyncio.CancelledError:
log.info('Received CancelledError exception')
exit_code = 0
break
# if and only if we received statistics from all sockets then move
# statistics to the permanent directory.
# NOTE: when temporary and permanent storage directory are on the same
# file-system the move is actual a rename, which is an atomic
# operation.
if result:
log.debug('move %s to %s', storage_dir, dst_dir)
try:
shutil.move(storage_dir, dst_dir)
except OSError as exc:
log.critical("failed to move %s to %s: %s", storage_dir,
dst_dir, exc)
log.critical('a fatal error has occurred, exiting..')
break
else:
log.info('statistics are stored in %s', os.path.join(
dst_dir, os.path.basename(storage_dir)))
else:
log.critical('failed to pull stats')
log.debug('removing temporary directory %s', storage_dir)
shutil.rmtree(storage_dir)
# calculate sleep time which is interval minus elapsed time.
sleep = config.getint('pull', 'pull-interval') - (time.time() -
start_time)
if 0 < sleep < config.getint('pull', 'pull-interval'):
log.debug('sleeping for %.3fs secs', sleep)
time.sleep(sleep)
# It is very unlikely that threads haven't finished their job by now, but
# they perform disk IO operations which can take some time in certain
# situations, thus we want to wait for them in order to perform a clean
# shutdown.
log.info('waiting for threads to finish any pending IO tasks')
executor.shutdown(wait=True)
log.info('closing our asyncio loop')
loop.close()
log.info('exiting with status %s', exit_code)
sys.exit(exit_code)
def main():
"""Parses CLI arguments and launches main program."""
args = docopt(__doc__, version=VERSION)
config = ConfigParser(interpolation=ExtendedInterpolation())
# Set defaults for all sections
config.read_dict(copy.copy(DEFAULT_OPTIONS))
# Load configuration from a file. NOTE: ConfigParser doesn't warn if user
# sets a filename which doesn't exist, in this case defaults will be used.
config.read(args['--file'])
if args['--print']:
for section in sorted(DEFAULT_OPTIONS):
print("[{}]".format(section))
for key, value in sorted(DEFAULT_OPTIONS[section].items()):
print("{k} = {v}".format(k=key, v=value))
print()
sys.exit(0)
if args['--print-conf']:
for section in sorted(config):
print("[{}]".format(section))
for key, value in sorted(config[section].items()):
print("{k} = {v}".format(k=key, v=value))
print()
sys.exit(0)
log.setLevel(getattr(logging, config.get('pull', 'loglevel').upper(),
None))
# Setup our event loop
loop = asyncio.get_event_loop()
# Register shutdown to signals
loop.add_signal_handler(signal.SIGHUP, shutdown)
loop.add_signal_handler(signal.SIGTERM, shutdown)
# a temporary directory to store fetched data
tmp_dst_dir = config['pull']['tmp-dst-dir']
# a permanent directory to move data from the temporary directory. Data are
# picked up by the process daemon from that directory.
dst_dir = config['pull']['dst-dir']
for directory in dst_dir, tmp_dst_dir:
try:
os.makedirs(directory)
except OSError as exc:
# errno 17 => file exists
if exc.errno != 17:
sys.exit("failed to make directory {d}:{e}".format(d=directory,
e=exc))
supervisor(loop, config)
# This is the standard boilerplate that calls the main() function.
if __name__ == '__main__':
main()