I'm trying to write script for gathering some information from network devices using Pexpect async expect(python 3.5.1 and pexpect from github) and get some strange thing: all works fine with several devices and doesn't work with some more (usually > 5-6). I wrote this simple script for testing:
@asyncio.coroutine def test_ssh_expect_async(num): print('Task #{0} start'.format(num)) p = pexpect.spawn('ssh localhost', encoding='utf8') #p.logfile = sys.stdout yield from p.expect('password', async=True) p.sendline('***') yield from p.expect(r'@self-VirtualBox\:', async=True) p.sendline('uptime') yield from p.expect(r'@self-VirtualBox\:', async=True) p.sendline('uname -a') yield from p.expect(r'@self-VirtualBox\:', async=True) p.sendline('ll') yield from p.expect(r'@self-VirtualBox\:', async=True) print('Task #{0} end'.format(num)) @asyncio.coroutine def test_loop(): tasks = [] for i in range(1, 5): tasks.append(test_ssh_expect_async(i)) yield from asyncio.wait(tasks) print('All Tasks done') print('--------------Async--------------------') loop = asyncio.get_event_loop() loop.run_until_complete(test_loop()) If i try to use range(1,3) as example i get this:
self@self-VirtualBox:/media/sf_netdev$ python3 simple-test.py --------------Async-------------------- Task #3 running Task #1 running Task #2 running Task #3 closed Task #1 closed Task #2 closed All Tasks done But if i increase upper limit i get some errors:
self@self-VirtualBox:/media/sf_netdev$ python3 simple-test.py --------------Async-------------------- Task #3 running Task #1 running Task #4 running Task #2 running Exception in callback BaseSelectorEventLoop.add_reader(11, <bound method...d=11 polling>>) handle: <Handle BaseSelectorEventLoop.add_reader(11, <bound method...d=11 polling>>)> Traceback (most recent call last): File "/usr/lib/python3.5/asyncio/selector_events.py", line 234, in add_reader key = self._selector.get_key(fd) File "/usr/lib/python3.5/selectors.py", line 191, in get_key raise KeyError("{!r} is not registered".format(fileobj)) from None KeyError: '11 is not registered' During handling of the above exception, another exception occurred: ... Why it happens? How to write working script with async pexpect?
---------------Answer------------
It was a bug https://github.com/pexpect/pexpect/issues/347. Now pexpect command fixed it.
