clinicjs / node-clinic-doctor-examples

Server examples for `clinic`

node-clinic-doctor-examples

Server examples for clinic

git clone [email protected]:nearform/node-clinic-doctor-examples.git
cd node-clinic-doctor-examples
npm install
npm install -g clinic
npm install -g autocannon

Examples

Event Loop

clinic doctor --autocannon [ / ] -- node slow-event-loop

GC

clinic doctor --autocannon [ -c 2500 / ] -- node slow-gc

I/O

clinic doctor --autocannon [ / ] -- node slow-io

Sync I/O

clinic doctor --autocannon [ / ] -- node sync-io

License

Apache 2.0

node-clinic-doctor-examples's Issues

prepare a demo case with node calling other http servers

doc: wrong command in slow event loop tutorial

On this page:
https://clinicjs.org/documentation/doctor/05-fixing-event-loop-problem/
It says to create a flame graph via:
clinic flame --on-port 'autocannon localhost:$PORT' -- node slow-io

But the command should perhaps be:
clinic flame --on-port 'autocannon localhost:$PORT' -- node slow-event-loop

Not sure if this is the proper place to report possible issues with the web site, so apologies if this is misplaced. Thanks!

use clinic doctor in the readme

Bad data issue

Hi!
For this node.js file:

const {performance} = require('perf_hooks');
const {eventLoopUtilization} = require('node:perf_hooks').performance;
setImmediate(() => {
    const start = performance.now();
    const elu = eventLoopUtilization();
    let sum = 0;
    for (let i = 0; i < 1000000; i++) {
        sum += i;
    }
    const end = performance.now();
    console.log(`ELU utilization: ${eventLoopUtilization(elu).utilization}`);
    console.log(`Elapsed time: ${(end - start).toFixed(2)} milliseconds`);
}); 

I get the message Bad Data:
Doctor has found data analysis issue:
Something went wrong with the data analysis
Try running the benchmark for a longer time
If the issue persists, open an issue at https://github.com/clinicjs/node-clinic-doctor
What exactly should be the fix?

Include in the readme examples where Doctor finds no problem

This is a documentation issue only.

If/when we find some good examples of real node packages that Doctor finds no fault with, it might be list an example or two the readme so that:

• Users can see what the data on a real-world "good" profile might look like
• Clinic developers can easily create realistic "no recommendation" profile when testing *

For example:

npm install [email protected]
clinic-doctor -- node path/to/some-perfect-package someArgument

Existing examples with no wrk or other activity on :3000 tend to come up as io issues because Doctor is suspicious of the lack of CPU activity.

slow-gc gives I/O alert highlighting CPU graph, even before heap limit change

Running Doctor on slow-gc gives a I/O alert and flags the CPU graph (expected a Garbage Collection alert flagging the Memory graph).

Strange thing is, it's not just Doctor after 3.9.0, Do not issue the GC category if the heap is smaller than 128MB. (#213).

Using clinic doctor --autocannon [/] -- node slow-gc on the following:

Doctor v3.8.1 (last release before the above):

• Mac, Node v11.3.0 - I/O alert - https://upload.clinicjs.org/public/6853562abc182b6077e86c0cc655049e035bcc7e6bd188005416386365fdd7f7/28353.clinic-doctor.html
• Mac, Node v10.14.1 - I/O alert - https://upload.clinicjs.org/public/c692a2d8377df75c650d3ff3acafe9503bbab5660cc307961404c727c1477d5e/31260.clinic-doctor.html
• Mac, Node v10.9.0 - I/O alert - https://upload.clinicjs.org/public/4e089ec2c323f0514ae2002b1a54ddf8809bc1d3da896b78358b20fcc2f9d100/28486.clinic-doctor.html
• Mac, Node v8.12.0 - I/O alert - https://upload.clinicjs.org/public/04874a62c9bab91d34ded7c42b3d692f1012894b3c3373555de5f0157eb5acbd/29988.clinic-doctor.html

Create an example of a callback called recursively

Based on a discussion with Mathias, we want to see how Bubbleprof handles common patterns where a callback is being called recursively, to see how we should best treat these in terms of sums, averages and quantiles.

So some application including something like (pseudocode)

fn a (n, callback)
  if (n > 0) setTimeout(a, n--, callback)
  else callback()