This can happen when adjusting a tmux pane running mininet cli. The
process will receive SIGWINCH causing the poll() call to raise
select.error
Below is a session dump with strace
09:55:52.498106 poll([{fd=0, events=POLLIN}, {fd=28, events=POLLIN}], 2, -1) = ? ERESTART_RESTARTBLOCK (Interrupted by signal)
09:55:52.606734 --- SIGWINCH {si_signo=SIGWINCH, si_code=SI_KERNEL} ---
09:55:52.606770 rt_sigreturn({mask=[]}) = -1 EINTR (Interrupted system call)
Traceback (most recent call last):
File "examples/topofac.py", line 527, in <module>
run()
File "examples/topofac.py", line 522, in run
CLI( net )
File "/home/yunion/git-repo/mininet/mininet/cli.py", line 68, in __init__
self.run()
File "/home/yunion/git-repo/mininet/mininet/cli.py", line 103, in run
self.cmdloop()
File "/home/yunion/.usr/lib/python2.7/cmd.py", line 142, in cmdloop
stop = self.onecmd(line)
File "/home/yunion/.usr/lib/python2.7/cmd.py", line 220, in onecmd
return self.default(line)
File "/home/yunion/git-repo/mininet/mininet/cli.py", line 422, in default
self.waitForNode( node )
File "/home/yunion/git-repo/mininet/mininet/cli.py", line 440, in waitForNode
bothPoller.poll()
select.error: (4, 'Interrupted system call')
09:55:52.622076 rt_sigaction(SIGINT, {SIG_DFL, [], SA_RESTORER, 0x7ff9a9b936d0}, {0x7ff9a9ef2230, [], SA_RESTORER, 0x7ff9a9b936d0}, 8) = 0
09:55:52.631905 +++ exited with 1 +++
Previously we looked for 'eth0', but linux has renamed interfaces.
Instead of looking by name, we now look for an interface which
is the appropriate gateway to a remote server address.
fixes#831
pmonitor() is hard to get right, but this seems like
a reasonable improvement:
1. non-blocking I/O so we can drain buffer with impunity
2. drain buffer after poll
3. unregister fd on POLLHUP
Note we may have a unicode splitting problem since we're
decoding chunks of bytes, but that is a problem for another
day I think.
Changes for compatibility with Python 3.
The approach is to make as few changes as possible to maintain compatibility with both Python 2 and Python 3.
We use whatever python is installed, and also support a PYTHON environment variable for installing another version.
For simplicity, we provide mininet.util.pexpect which works out of the box with Python 3 utf-8 strings.
Thanks to @cuihantao for looking at this as well and also for changes to MiniEdit.
Closes#794
items() vs. iteritems() and decode() bytes in monitorFiles
Probably not strictly correct if bytes are split - we still
need to deal with this properly.
Unfortunately pexpect isn't compatible with Python 3 strings
unless you specify unicode encoding, which isn't the default.
With this helper code, you can import pexpect from mininet.util
and get default pexpect.spawn() behavior that works with Python 3
strings.
lantz
Yousong Zhou
gabay
Theo
Hantao Cui