Pending AIO operation, recycle later...
 

Issue: Litespeed became non-responsive suddenly, websites couldn't be accessed. After restart, litespeed worked again.

The issue occurred three times.

Log: I checked litespeed logs, found lots of "Pending AIO operation, recycle later..." message when litespeed was not responsive.

The server has 48GB ram, AIO is enabled and AIO block size is 8M.

Was AIO cause the issue? How to solve the issue please?

how long of the period when it occurred 3 times? within one day, one week?

you can disable AIO for some time, so can do comparison.

It occurred every 20 hours.. around 20 hours.

I don't know if it will occur again, the server has been running for more than 1 year and the issue began from the day before yesterday.

check error log and see any indication around the time lsws became unresponsive.