My system is running CentOS 7.6, lsyncd-2.2.2 and rsync-3.1.2, with 8G RAM.
Today I needed to reboot the system (to change some mount points).
30 min after the boot, noticed my applications stopped responding.
Upon checking, found system with very little available memory.
The command "ps axo rss,vsz,%mem,pid,cmd | sort -n" showed lsyncd used 4G of RAM.
Have read about each inotify folder uses 1K. The system has less than 22,000 folders. So 22M.
Question is what might be occupying the other 3980 M of memory?
I suspect that some unusual conditions caused lsyncd startup to used 4G RAM.
If lsyncd always uses that much memory on startup, I would have noticed. My applications cannot survive such impact.
What factors, e.g. presence of large un-synced files, may cause lsyncd startup to use large amount of memory?
On that note I found a few large files totalling 2.7G and deleted them. Did not help.
Lastly, to restore the system, I have stopped and started lsyncd several times, each time when it creeped pass 3G memory.
Finally I stopped all my applications and just leave lsyncd with all the memory. It reached 3.6G RAM before settled down to 84M.
Thanks for help.