Bug caused by joining the "!****:matrix.org" room with over 100,000 people

[matrixbot]

This issue was originally created by @simontxxx at matrix-org/dendrite#3375.

Background information

• Dendrite version or git SHA: 46902e5
• SQLite3 or Postgres?: Posgtres
• Running in Docker?: no
• go version: 1.22.2
• Client used (if applicable): Element

Description

• What is the problem: CPU usage is high. <input.(*Inputer).processRoomEvent> Missing event has missing prev events". Many log "Failed to get missing /event for event ID". There is a problem with message consumption in Nats, and messages are starting to get stuck. This is causing the recipient to not receive messages when they are sent. Removed the jetstream directory of nats and restart dendrite to recover.
• Who is affected: "Me" - Who are you? Running the server or a user on a Dendrite server?
• How is this bug manifesting: “Can't send messages"
• When did this first appear:

Steps to reproduce