Issue https apache throughput very weak

[Gabor H]

Hi,

I've a fresh install of Ubuntu 16.04 LTS + Plesk Onyx 17.5.3.
If I add a domain and make a http load test with `ab` command, then I see that max possible request which the system can handle is around 1700-2100 req/sec.

If I add an ssl cert from Plesk with Let's Encrypt, and make again load test with `ab`, then the max load
is around 4-6 req/sec max.

Why is it dropping so much?
I guess it must e some kind of config issue. But on which way to go on, what to check and change config to get the max available https req/sec?

Anyway, what would be the ideal possible max req/sec on a nginx+php-fpm in my case with https, when with http it's around 1700-2100 req/sec?

Thanks in advance.

 

[Bitpalast]

Besides the encryption/decryption process, specifically the SSL handshake can take some while. I'd assume that only the first request of a connection is slower and all the following are almost as fast as non-SSL requests. The question is: What exactly does the test software do? If it acts as a new client each time a resource is requested, then the server needs to do the SSL handshake over and over again. This is time consuming.

 

[Gabor H]

Besides the encryption/decryption process, specifically the SSL handshake can take some while. I'd assume that only the first request of a connection is slower and all the following are almost as fast as non-SSL requests. The question is: What exactly does the test software do? If it acts as a new client each time a resource is requested, then the server needs to do the SSL handshake over and over again. This is time consuming.

Ok, understand that because of the handshake it will consume some time, but based on the loader.io website's stress test, it also point out that the max throughput is around 4-6req/sec, same range as `ab` tested.

Question is, that adding an SSL via the Let's Encrypt plugin would work like a charm without additional tweaking of the Plesk's config system, or are there any config which needed to make in order to be able to get high load? 4-6req/sec is way too low...

 

[Gabor H]

Additional info:
When the domain is jut added into Plesk, with the Lets Encrypt cert enabled, and only one Plesk's default landing page is loaded, then in this case the https throughput is around 150-200 req/sec.

But when an "empty", fresh install of Prestashop is installed, then the https throughput drops to the 4-6req/sec max rate.
But why?

 

[Bitpalast]

Did you check that no redirects are taking place? Doesn't Prestashop use an .htaccess file with some rewrite rules?

 

[Gabor H]

You can use Presta with Nginx as well. It's not only tied to Apache/.htaccess.
Nginx config is available for Presta.

So it's a different kind of issue.
But I still don't know which, and where to look for the solution.
I've already updated the SSL cyphers to a fast one, but not a major change in throughput.

Did you check that no redirects are taking place? Doesn't Prestashop use an .htaccess file with some rewrite rules?