[j-nsp] PYEZ module hangs

[serge vautour]

Hello,

I'm having problems with the import of PYEZ module hanging. My python
script:

from jnpr.junos import Device
def main():
 blah = ""

if __name__ == "__main__":
    main()

That's as simple as possible. When I remove the "from jnpr.junos" line, the
problem described below goes away.

When I run this using a unix for loop I get:

[root at xxxx]# for i in {1..100}; do echo $i;time python test.py ; done
1

real    0m0.725s
user    0m0.635s
sys     0m0.092s
2

real    0m0.647s
user    0m0.567s
sys     0m0.082s
3

real    0m0.654s
user    0m0.573s
sys     0m0.084s

etc...

Eventually, and this appears completely random, it will hang:

35

real    0m0.650s
user    0m0.572s
sys     0m0.079s
36
^\Quit

real    0m27.527s
user    0m0.360s
sys     0m0.059s
37
^\Quit

real    0m11.761s
user    0m0.350s
sys     0m0.067s
38
^\Quit

real    0m51.663s
user    0m0.357s
sys     0m0.062s

The ^\Quit is me killing that instance of the python script with ctrl-\. If
I wait long enough it unblocked by itself:

39

real    2m55.709s   <--- It eventually unblocked on it's own
user    0m0.588s
sys     0m0.079s
40

real    0m0.647s
user    0m0.573s
sys     0m0.076s
41

real    0m0.647s
user    0m0.575s
sys     0m0.074s
42

How long it takes once hung is random. How often it hangs is random.
Sometimes I can run it over a 1000 times without an issue.

I am on the latest version of python and of the module (I think):
[root at xxxxxx# python
Python 2.7.5 (default, Feb 20 2018, 09:19:12)
[GCC 4.8.5 20150623 (Red Hat 4.8.5-28)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> from jnpr.junos import version
>>> print version.VERSION
2.2.0

Just today I ran the PIP command to update PYEZ and all dependencies. The
problem is still present.

This is running on a VM with lots of resources (32G RAM, 8CPU). top shows
less than 1G RAM in use and nearly no CPU usage even with it hangs. I have
tried running the same code on a different VM (on a different physical
chassis) with the same version of python and PYEZ and cannot reproduce.

Any suggestions on how to troubleshoot this? Is it possible it's the
underlying VM Hardware or virtualization software?

Thanks,
Serge