How to debug when OS kills postgres for high memory usage

Question

I am running Postgres 9.4 server in a VPS running Ubuntu. It gets killed often (multiple times in a day).

This is the message from dmesg

Out of memory: Kill process 1020 (postgres) score 64 or sacrifice child

Killed process 1020 (postgres) total-vm:445764kB, anon-rss:140640kB, file-rss:136092kB

How to debug what is causing this crash? Is it long running queries or some misconfiguration of the server or lots of idle connections open?

Answer 1

It's the OOM killer in the Linux kernel. Disable VM overcommit, per the advice in the PostgreSQL manual.