Agent的错误日志表现如下：
[18/Nov/2014 21:12:56 +0000] 22681 MainThread agent ERROR Heartbeating to master:7182 failed. Traceback (most recent call last): File "/home/opt/cm-5.2.0/lib64/cmf/agent/src/cmf/agent.py", line 820, in send_heartbeat response = self.requestor.request('heartbeat', dict(request=heartbeat)) File "/home/opt/cm-5.2.0/lib64/cmf/agent/build/env/lib/python2.6/site-packages/avro-1.6.3-py2.6.egg/avro/ipc.py", line 139, in request return self.issue_request(call_request, message_name, request_datum) File "/home/opt/cm-5.2.0/lib64/cmf/agent/build/env/lib/python2.6/site-packages/avro-1.6.3-py2.6.egg/avro/ipc.py", line 255, in issue_request return self.read_call_response(message_name, buffer_decoder) File "/home/opt/cm-5.2.0/lib64/cmf/agent/build/env/lib/python2.6/site-packages/avro-1.6.3-py2.6.egg/avro/ipc.py", line 235, in read_call_response raise self.read_error(writers_schema, readers_schema, decoder) File "/home/opt/cm-5.2.0/lib64/cmf/agent/build/env/lib/python2.6/site-packages/avro-1.6.3-py2.6.egg/avro/ipc.py", line 244, in read_error return AvroRemoteException(datum_reader.read(decoder)) File "/home/opt/cm-5.2.0/lib64/cmf/agent/build/env/lib/python2.6/site-packages/avro-1.6.3-py2.6.egg/avro/io.py", line 444, in read return self.read_data(self.writers_schema, self.readers_schema, decoder) File "/home/opt/cm-5.2.0/lib64/cmf/agent/build/env/lib/python2.6/site-packages/avro-1.6.3-py2.6.egg/avro/io.py", line 448, in read_data if not DatumReader.match_schemas(writers_schema, readers_schema): File "/home/opt/cm-5.2.0/lib64/cmf/agent/build/env/lib/python2.6/site-packages/avro-1.6.3-py2.6.egg/avro/io.py", line 379, in match_schemas w_type = writers_schema.type AttributeError: 'NoneType' object has no attribute 'type'