FlowVisor getSliceStats error

[jbsbbn]

We talked about this in an e-mail conversation; here's a ticket for it, copying things from the e-mail thread.

From: Josh Smift <[email protected]> 
To: [email protected], Nick Bastin <[email protected]> 
Cc: GPO Infrastructure Folks <[email protected]> 
Subject: [gpo-infra] FlowVisor getSliceStats error 
Date: Tue, 19 Mar 2013 09:28:04 -0600 

When tango-monitor-foam's metric_foam script asks FOAM to ask FlowVisor 
for stats, it sometimes says 

  Error (<Fault 0: 'Failed to invoke method getSliceStats in class org.flowvisor.api.FVUserAPIXMLRPCImpl: null'>) received while querying FOAM status: Traceback (most recent call last): 
File "/usr/bin/metric_foam", line 70, in report_foam_status 
  foammetric.collect_metrics() 
File "/usr/local/lib/foam_metrics.py", line 317, in collect_metrics 
  self.get_flowvisor_metrics() 
File "/usr/local/lib/foam_metrics.py", line 308, in get_flowvisor_metrics 
  self.flowvisor_metric.collect_metrics() 
File "/usr/local/lib/flowvisor_metrics.py", line 575, in collect_metrics 
  self.get_slice_stats(slice) 
File "/usr/local/lib/flowvisor_metrics.py", line 527, in get_slice_stats 
  api_result = self._api_call_getSliceStats(slice) 
File "/usr/local/lib/flowvisor_metrics.py", line 251, in wrapped_api_call 
  result = apicall(*args, **kwargs) 
File "/usr/local/lib/flowvisor_metrics.py", line 277, in _api_call_getSliceStats 
  return self.api.getSliceStats(slice) 
File "/usr/lib/python2.6/xmlrpclib.py", line 1199, in __call__ 
  return self.__send(self.__name, args) 
File "/usr/lib/python2.6/xmlrpclib.py", line 1489, in __request 
  verbose=self.__verbose 
File "/usr/lib/python2.6/xmlrpclib.py", line 1253, in request 
  return self._parse_response(h.getfile(), sock) 
File "/usr/lib/python2.6/xmlrpclib.py", line 1392, in _parse_response 
  return u.close() 
File "/usr/lib/python2.6/xmlrpclib.py", line 838, in close 
  raise Fault(**self._stack[0]) 
  Fault: <Fault 0: 'Failed to invoke method getSliceStats in class org.flowvisor.api.FVUserAPIXMLRPCImpl: null'> 

We've gotten this three times in the past twelve hours or so; the first 
was that one, the other two were identical except they said 

  Error (<Fault 0: ''>) received while querying FOAM status: Traceback (most recent call last): 

but the rest of the stacktrace was the same. 

We don't think we've ever seen these before yesterday.

There was some speculation that this had something to do with a FlowVisor with no slices, or perhaps a slice that was disconnected from its controller, but I don't think anyone ever tested either of those scenarios to confirm or deny that we could reproduce this error in those cases.