Error 503 and website stoped working for couple hours

Hi,

There is a store with ~500 products and today i have warning from host that cpu limit was exceeded.

At first, when entering the site, error 503 randomly appeared and after some time the page stopped loading at all. It lasted for several hours. At the crucial moment, there were 15k HTTP Queries to www.website.pl/ajax/cart.json?_=123456789 on the site within minutes and CPU resource consumption has gone over the limit. There are no warnings or fatal errors in error log (i think because when time limit is exceded the error is not logged) and performance log also looks good.

lc_cart_items table contains ~70k records.

In the Apache (LiteSpeed) error log there are tons of entries like below:

[quote]2022-02-23 16:26:13.519889 [INFO] [859236] [T0] [11.22.33.44:25959-H3:65DF0321CD21DA59-52#APVH_www.website.pl:443] abort request..., code: 4
2022-02-23 16:28:54.329157 [INFO] [859239] [T0] [55.66.77.88:45496:HTTP2-1#APVH_www.website.pl:443] Abort request processing by PID:1072883, kill: 1, begin time: 5, sent time: 5, req processed: 0[/quote]

Where could the problem be? Maybe someone had a similar situation?

Server is LiteSpeed + MariaDB + tried PHP from 7 to 7.4

TIA

Looks like you were targeted for some sort of attack. Make sure your firewalls tackles traffic floods. If that is not the reason for the cpu rise then there coule be a memory leak in your php version. But since you were under attack it's higly likely due to the attack.