Environment

• YugabyteDB Affected Versions:
  • 2.14 Branch: < 2.14.15.0
  • 2.16 Branch: < 2.16.9.0
  • 2.18 Branch: < 2.18.5.0
  • 2.20 Branch: < 2.20.1.0
    

Issue

A user has a low number of current connections on a universe, but when attempting to establish a new connection using ysqlsh the user receives an error:

ysqlsh: FATAL: remaining connection slots are reserved for non-replication superuser connections

This may be related to GH-18265, GH-18272, or GH-19945, where, after a postgres process is killed, the files and mechanisms used to monitor connections limits aren't properly cleaned up on process restart, and so postgres believes that the connections are at the maximum. 

Likely, this is due to a past OOM event where the number of connections did hit the maximum and the postgres process was killed by the OOM-killer.

Resolution

Overview

For affected versions, the resolution likely requires either of the two options:

1. A Rolling Restart
2. Pausing and Resuming the Universe

This should cleanup the files and counters that track the connections. 

If neither option resolves the issue, please create a ticket with YB Support for further assistance.

Steps

Option 1: Perform a Rolling Restart

• On the Universe, click: Actions > Initiate Rolling Restart

Option 2: Pause and Resume the Universe

1. On the Universe, click: Actions > Pause Universe
2. Once the Pause succeeds, click: Actions > Resume Universe

If neither option resolves the issue, please create a ticket with YB Support for further assistance.