Thousands of users disconnected at the same time with "Client limit exceeded: 20000"

[progval]

Hi,

Describe the bug

I have noticed a few times on Libera that the bridge would disconnect many users at the same time, with "Quit: Client limit exceeded: 20000".

Yesterday, they were thousands, flooding backlogs of anyone without quit/join filtering.

To Reproduce

No idea

Expected behavior

Shed users progressively, spaced over either regular or random intervals

Screenshots

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Desktop (please complete the following information):

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Additional context

[Half-Shot]

Hiya, we hit our limit of connections with libera again last night which caused this problem. Normally, we do inactive users over a much more controlled period.

[progval]

This is not an isolated issue. It also happened twice on 2021-07-02, and once on 2021-11-12 and 2021-11-18.

[Mikaela]

How about disconnecting dead bridges that are not coming back? #1460