Elastic search using more RAM and not release

[xgx]

Hi,
I have a problem with elastic search uses a lot of os memory (non buff / cache).Here are some details：
1.I am using a 64 GB Ram machine .
2.I have allocated 26gb as ES heap size.
3.only elasticsearch service running on machine.

After running for a while， I see that elastic search is using up most of the RAM,

Meanwhile ，Of the 26 GB heap space allocated, only 16 GB has been used up.
I noticed that in the process mapping file / proc / PID / smaps, elastic search has applied for about 500 anonymous memory spaces with the size of 50MB.

Is this the behavior of elastic search or Lucene? Is it normal?

[warkolm (Mark Walkom)]

This is the OS doing what is should do and is caching constantly used files in memory.