RAM usage increase by the time

[rajeshisnepali]

Describe the bug
For instance, current (Sun Aug 14, 2:00 UTC) RAM usage is 3GB, later (Sun Aug14, 8:00 UTC) RAM usage is 3.1GB or can be more.

To Reproduce

• Install nominatim using latest docs in a high configuration server
• Import North America map data https://download.geofabrik.de/north-america-latest.osm.pbf
• Backup database & migrate to a lower-end server using https://nominatim.org/release-docs/latest/admin/Advanced-Installations/#moving-the-database-to-another-machine
• run nominatim in another (lower-end) server
• wait for few hours or days to see the increase in RAM.

Software Environment (please complete the following information):

• Nominatim version: Nominatim-4.0.1
• Postgresql version: PostgreSQL 12.11
• Postgis version: I didn't find HINT: No function matches the given name and argument types. You might need to add explicit type casts.
• OS: ubuntu 20.04

Hardware Configuration (please complete the following information):

• RAM: 8GB
• number of CPUs: 2
• type and size of disks: gp2 storage & 400GB
• bare metal/AWS/other cloud service:

Postgresql Configuration:

   shared_buffers = 2GB
   maintenance_work_mem = 1GB
   autovacuum_work_mem = 2GB
   work_mem = 6MB
   effective_cache_size = 3GB
   synchronous_commit = off
   max_wal_size = 1GB
   checkpoint_timeout = 10min
   checkpoint_completion_target = 0.9
   autovacuum_max_workers = 1

Additional context

I recently noticed that issue after my app was down. And then monitored my RAM usage.

[rajeshisnepali]

Update

[lonvia]

There is nothing unusual going on here. Postgresql loads more and more data with time which ends up in the buffer cache.

[rajeshisnepali]

So that means I've to manually restart my server periodically to clear the buffer cache?

[mtmail]

You can limit the size of the buffer https://www.postgresql.org/docs/12/runtime-config-resource.html

[rajeshisnepali]

I don't think it is working.