Soft OOM support¶

since 1.4.2

Sometimes, even when using a connection pooler, you may encounter Out Of Memory (OOM) situations on the PostgreSQL server. In such cases, it is advisable to temporarily suspend accepting new connections until PostgreSQL’s memory consumption returns to a normal level. To address this, we have implemented a "soft OOM" mechanism, which is described in detail below. This mechanism helps prevent further overloading the database by gracefully managing new connection attempts during memory pressure events.

Soft OOM makes sense only for connections that is not local, that means, that Odyssey console will still works when your host is in OOM state.

Configuration¶

First of all you will need describe memory limitations in soft-oom section at the root of configuration:

# for specified process
soft_oom {
    process 'postgres'
    limit   750MB
}

# for whole system
soft_oom {
    limit   750MB
}

# top memory consumers terminating

soft_oom {
    limit 750MB

    drop {
        signal 'SIGTERM'
        max_rate 2
    }
}

After that, all new connections to db.user will be answered by Odyssey itself process described in soft_oom reached limit by total memory consumption:

psql 'host=localhost port=6432 user=postgres dbname=postgres sslmode=disable' -c 'select 42'
psql: error: connection to server at "localhost" (::1), port 6432 failed: Connection refused
    Is the server running on that host and accepting TCP/IP connections?
connection to server at "localhost" (127.0.0.1), port 6432 failed: FATAL:  odyssey: cbde8d0203caf: soft out of memory