How to work with strace?

Question

Debugging

There is a site. Worked pretty well until today. After dinner, he began to shamelessly blunt.
100% CPU, LA > 10.
Nothing interesting in the logs.
I watch strace - and I understand that I do not understand anything.
Dear, be grateful, share materials on the topic - how and where, what to look at in strace / trace?

Answer 1

Do not immediately climb into the wilds, strace will not give you anything.
First, look at:
1) What process is loading the percent (top, htop, etc.)
2) Is the traffic in the http server logs different from the previous one and from the expected one.
3) Network traffic, whether it differs from the previous one and from the expected one.
And only then draw conclusions. Maybe they just posted an uber article on the site that attracted 100,500 people