title: what is the log format of elastic search?
body: <p>Sample Format of elasticsearch log: <code>[2017-08-30T06:27:19,158][WARN ][o.e.m.j.JvmGcMonitorService] [Glsuj_2] [gc][296816] overhead, spent [1.2s] collecting in the last [1.3s]</code></p>
  
  <p>Can you please explain me what does it mean? when we observe the log?
  please explain me each and every word in the log?</p>
  
  <p>what is meant by <code>o.e.m.j.JvmGcMonitorService</code> ?</p>
  
  <p>what is meant by <code>Glsuj_2</code>?</p>
  
  <p>what is meant by <code>gc</code>?</p>
  
  <p>what is meant by <code>296816</code>?</p>