Abnormal index_writer_memory,its so high!

[KellyK313]

Our ElasticSearch version is v1.6.2.
31G jvm memory in 156G machine total memory.
Recently I found out our node is OOM frequently,then I found an index use "index_writer_memory" is so high.

It really confuse me,because this index is not a bigdata index,look below.

and at the memory flood out time,the index rate is not high at all.

Can anybody tell me whats going on and how can I fix this problem?

[DavidTurner]

@KellyK313

Our Elasticsearch version is v1.6.2.

This version reached the end of its life many years ago, and more recent versions have seen big improvements in resiliency. The very first thing you should do is upgrade.

[KellyK313]

I know the version is out of times,but this problem is in our production environment so I have to fix it first.