Accessing await ctx.session() seems awkwardly slow

[gregorkrambs]

I was benchmarking my mojo.js app and found a huge bottleneck. I didn't expect calling

await ctx.session()

to slow down an application by factor 750x. To reproduce my observations, I freshly created an empty mojojs app and benchmarked it.

Running the default mojojs full app with NODE_ENV=production node index.js server: ~15,932 requests /sec

wrk -t1 -c1 -d10 http://localhost:3000
Running 10s test @ http://localhost:3000
  1 threads and 1 connections
  Thread Stats   Avg      Stdev     Max   +/- Stdev
    Latency   113.41us  742.27us  20.38ms   99.08%
    Req/Sec    16.02k     2.28k   17.59k    90.10%
  160899 requests in 10.10s, 96.06MB read
Requests/sec:  15932.80
Transfer/sec:      9.51MB

After adding await ctx.session() to the main route: ~21 requests /sec

wrk -t1 -c1 -d10 http://localhost:3000
Running 10s test @ http://localhost:3000
  1 threads and 1 connections
  Thread Stats   Avg      Stdev     Max   +/- Stdev
    Latency    48.13ms   10.44ms 171.47ms   97.65%
    Req/Sec    20.78      4.27    30.00     82.83%
  211 requests in 10.09s, 165.66KB read
Requests/sec:     20.90
Transfer/sec:     16.41KB

I tested this with various setups (single threaded vs multi threaded, cluster mode and non-cluster mode, different machines: Mac OS X and Debian) but the huge difference between calling the session vs not calling the session was always huge.

While I expect the AES decryption to take some time, ~20 requests per second on a single thread (or ~600req/sec on a 64 core machine) for an empty app with just a session call is not very satisfying.

Am I doing something wrong here?

This can be reproduced by simply adding const session = await ctx.session(); to the welcome route in the example controller of npm create @mojojs/full-app.

export default class Controller {
  // Render template "example/welcome.html.tmpl" with message
  async welcome (ctx) {
    const session = await ctx.session();

    ctx.stash.msg = 'Welcome to the mojo.js real-time web framework!';
    await ctx.render();
  }
}

[kraih]

Crypto can be slow. We'd need some profiling data to see if there is a bug somewhere.