(The reason I did that is that the anti-crawler protections also unfortunately hit some legit users, and we don't want to block legit users. However, it seems that I turned the knobs down too far.)
In this case, though, we had a secondary failure: PagerDuty woke me up at 5:24am, I checked HN and it seemed fine, so I told PagerDuty the problem was resolved. But the problem wasn't resolved - at that point I was just sleeping through it.
I'll add more as we find out more, but it probably won't be till later this afternoon PST.
Edit: later than I expected, but for those still following, the main things I've learned are (1) pkill wasn't able to kill SBCL this time - we have a script that does that when HN stops responding, but it didn't work, so we'll revise the script; and (2) how to get PagerDuty not to let you go back to sleep if your site is actually still down.
1. Blame: The first thing to do is to point the finger. That doesn't mean analysing the technical issue, which can delay this step and limit your options, but figuring out who is politically easiest to blame. Often, that's the new guy, but outside contractors and vendors without good connections are also a common solution. Even if you are technically responsible for hiring them, you can always push them under the bus with a little skill. This small sacrifice helps unify, focus, and motivate the rest of the team.
2. Emotion: Inject your emotion into the situation and make that the implicit, but indisputable priority. Particularly, outrage and anger - This is completely _____. These people are utterly _____ (I'd use all caps, but that's not allowed on HN). Make sure everyone's attention is over their shoulder, on your emotion, and infect the team with it. Threats are an effective tool here - this is a crisis, and anyone who is calm is not emotionally engaged. Otherwise, they won't care enough about this problem - without you driving them, they probably wouldn't care much at all. Anyway, you don't have time for niceties like empathy or even basic respect.
3. Speed: Respnsiveness to stakeholders is very important. People need answers now. Give them answers they want to hear, outcomes they will be comfortable with. Don't worry if different groups hear different things. Your team will find a way to make it all work - that's their job.
4. Communication: Good communication is essential. Make sure you clearly tell your team what they should be doing; repeat it several times to prevent misunderstanding. Especially people with experience can have minds of their own; keep them on track. The situation is a crisis so you can't take any risks; stay on top of them and everything they do, and give input if you're not certain they are doing exactly what you would be doing.
5. Victimhood: Find a way to turn the tables: Make it about you, and how you're the victim here, and feed the fire with more outrage. With this and outrage, nobody will undermine the team by challenging your ideas or authority, which is the most essential component of a successful outcome. Remember, without you this all falls apart.
Have I missed anything?