Fix memory leaks

For one, configmanager was left with stale callback references, clean
those up.

For another, the callback pattern was creating a circular reference that
python memory management couldn't overcome.  Break the reference
explicity when an item is disposed of.

confluent_server/confluent/consoleserver.py

@@ -413,6 +413,9 @@ class ConsoleHandler(object):
         if self.connectionthread:
             self.connectionthread.kill()
             self.connectionthread = None
+        if self._attribwatcher:
+            self.cfgmgr.remove_watcher(self._attribwatcher)
+            self._attribwatcher = None
 
     def get_console_output(self, data):
         # Spawn as a greenthread, return control as soon as possible

confluent_server/confluent/plugins/hardwaremanagement/ipmi.py

@@ -292,6 +292,7 @@ class IpmiConsole(conapi.Console):
             self.solconnection.out_handler = _donothing
             self.solconnection.close()
         self.solconnection = None
+        self.datacallback = None
         self.broken = True
         self.error = "closed"
 

confluent_server/confluent/plugins/shell/ssh.py

@@ -63,6 +63,7 @@ class SshShell(conapi.Console):
     def __init__(self, node, config, username='', password=''):
         self.node = node
         self.ssh = None
+        self.datacallback = None
         self.nodeconfig = config
         self.username = username
         self.password = password
@@ -155,6 +156,7 @@ class SshShell(conapi.Console):
     def close(self):
         if self.ssh is not None:
             self.ssh.close()
+        self.datacallback = None
 
 def create(nodes, element, configmanager, inputdata):
     if len(nodes) == 1:

confluent_server/confluent/shellmodule.py

@@ -116,6 +116,7 @@ class ExecConsole(conapi.Console):
                 break
         if self.subproc is not None and self.subproc.poll() is None:
             self.subproc.kill()
+        self._datacallback = None
 
 
 class Plugin(object):