Low concurrent users cap with SSR

[nealalpert]

We were stress testing our next.js app and we're running into a rather low cap for the number of concurrent connections. For the initial GET request we're using next.js and express to serve up a server side rendered index page.

We're implementing some analytics at the moment to try and get a better idea about what our bottleneck is but I was wondering if there was anyone who has experienced a similar problem.

[sergiodxa]

The server render is a synchronous task, because of that it block the event loop of node.js, you must run multiple instances of your next app to serve many users, you can also avoid rendering some parts to reduce the time it takes to server render and set a cache.

In the example folder there are examples of progressive render (avoid rendering some parts) and cache.

[nealalpert]

Thank you very much for the quick reply! I think caching the SSR will be our next step.

[arunoda]

Thanks @sergiodxa for the help.

[nealalpert]

Implementing server side render caching dramatically lowered our CPU usage on our VM as expected but didn't increase concurrency during testing.

[jancel]

Is there any other advice to increase the concurrency? It seems that it just hugs around 5 requests per second, even if we throw 100 concurrent requests at it. Is this a nextjs side effect? It doesn't seem to fail at a higher clip, just doesn't process as much as we'd like to see.

[jancel]

A little more about the environment. Caddy on Lightsail -> Amazon ELB -> Amazon Linux Node v4.0.0 -> Node Version 6.9.X

Utilizing LRU cache in the node app really increased the server performance (CPU hangs around 1%).

We are using Sticky Session, because of an issue with navigation on the opposite.

We are using Hey to test successfully. Apache Benchmark doesn't have tolerance and fails > 50%.

[sergiodxa]

I think is not a side effect of next.js, it's more a side effect of React server render being synchronous. Maybe you can try using Preact for production which is supposed to render faster than React.

In my experience mounting a basic React server render you can take 200ms or more for rendering a normal page. So to improve that you can:

1. render less things server side
2. cache your server side rendered pages
3. have more instances of your server and use a load balancer
4. use Preact or Inferno to render faster

[jaspersorrio]

Hello @sergiodxa, just needed to clarify.

For:
4. use Preact or Inferno to render faster

Does this still stand with react 16?

Just curious and hope to know your opinions.

Thanks!

[davidgarsan]

Yep, recently I worked in a three ways benchmark with Vue v2.5, React 16.2 and Inferno 4, and Inferno was in another league. Other things like limited ecosystem aside, which is a drawback for big projects, Inferno was clearly the fastest one.