title: With logstash how to combine lines starting with timestamp
body: <p>Here is my sample log file which i need to parse using logstash: </p>
  
  <pre><code>2016-12-27 07:54:38.621 8407 ERROR oslo_service.service Traceback (most recent call last):
  2016-12-27 07:54:38.621 8407 ERROR oslo_service.service   File "/usr/lib/python2.7/dist-packages/oslo_service/service.py", line 680, in run_service
  2016-12-27 07:54:38.621 8407 ERROR oslo_service.service     service.start()
  2016-12-27 07:54:38.621 8407 ERROR oslo_service.service   File "/usr/lib/python2.7/dist-packages/nova/service.py", line 428, in start
  2016-12-27 07:54:38.621 8407 ERROR oslo_service.service     self.binary)
  2016-12-27 07:54:38.621 8407 ERROR oslo_service.service   File "/usr/lib/python2.7/dist-packages/oslo_versionedobjects/base.py", line 181, in wrapper
  </code></pre>
  
  <p>Please give me some suggestions how can i parse logs of this format using grok multiline filter and what pattern should i use for this.</p>
  
  <p>Thank you in advance !!</p>