Benchmarking.md

Benchmarking

mobx-quick-tree is designed to be fast, so, we have some benchmarks set up to help understand how fast it really is in the bench folder!

Running benchmarks

You can run a benchmark file with pnpm x <the file>:

pnpm x bench/instantiation.benchmark.ts

This will run the file and output a speed measurement for comparison between git branches.

You can also run all the benchmarks with:

pnpm x bench/all.ts

Profiling

It's nice to use the benchmarks for profiling to identify optimization candidates.

CPU profiling

The benchmark framework supports a --profile option for writing a profile of the benchmark loop, excluding setup and teardown code. Run a benchmark with profile, then open the created .cpuprofile file:

pnpm x bench/instantiation.benchmark.ts --profile

You can also run a benchmark to generate a profile using node.js' built in sampling profiler

node -r ts-node/register/transpile-only --prof bench/create-large-root.ts

node.js built in reporting

node --prof-process isolate-*.log

Flamegraphs

You can postprocess the generated isolate-0x<something>.log file into the data flamegraph expects, and then feed it to flamegraph to see a visual breakdown of performance. You can do that in one command like so:

node --prof-process --preprocess -j isolate-*.log | pnpm flamebearer

CPU profiling with VSCode

You can also use the profiler built into VSCode for executing scripts and profiling them. There's an example launch.json task in launch.json for running a script. You can also use console.profile() and console.profileEnd() to programmatically start a CPU profile in a benchmark while working on it.

deoptigate

deoptigate is a powerful tool for analyzing how compliant with V8's optimizations our code is. Run a script through deoptigate by first building the TS into JS with pnpm build, then run deoptigate on the script:

pnpm build
pnpm deoptigate dist/bench/create-many-model-class.js