what is the log format of elastic search?

Question

Sample Format of elasticsearch log: [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]

Can you please explain me what does it mean? when we observe the log? please explain me each and every word in the log?

what is meant by o.e.m.j.JvmGcMonitorService ?

what is meant by Glsuj_2?

what is meant by gc?

what is meant by 296816?

Answer 1

The log messages are composed within the JvmGcMonitorService class. I think this is the best place to lookup the logging semantics. A trouble ticket asking for documentation on github is still open.

This also applies to the more involved warnings, like the SLOW_GC_LOG_MESSAGE.

Answering (parts of) your question directly

o.e.m.j.JvmGcMonitorService - the abbreviated qualified name of the logging class

Glsuj_2 your node name

gc - "Garbage collection" - 'gc' is hardcoded in the log string

296816 - a sequence number, incremented when the gc is monitored

But the interesting part of the log starts after it: spent [1.2s] collecting in the last [1.3s]. Again: the parts inside the brackets are filled in by the JvmGcMonitorService.