file watching benchmarks

With the fanfare surrounding the release of chokidar@3.0.0, and the subsequent long list of new bugs which affected some of my projects, I decided to take a look at the issue of watching files. Long story short, watchboy was born and he's magnificent!

To make sure that he's doing a good job watching after your files, I created this benchmark suite. While I wrote and ran it, I am making it available to everyone so that you can check my work. Feel free to run it and submit more test cases that you want to see compared. With that said, let's talk about results.

Note: all memory measurements were taken after garbage collection.

Test machines

Tests are run in Azure Pipelines, for repeatability. The following specs are used (I will simply be referring to these machines as Windows, Linux and MacOS below):

OS	Processor	Cores
Microsoft Windows Server 2019 Datacenter	Intel(R) Xeon(R) CPU E5-2673 v4 @ 2.30GHz	2
Ubuntu 16.04.6 LTS	Intel(R) Xeon(R) CPU E5-2673 v4 @ 2.30GHz	2
macOS 10.14.6	Intel(R) Xeon(R) CPU E5-1650 v2 @ 3.50GHz	4

Now, let's watch some popular projects and see what kind of results we get. In all cases, I have pinned the exact commit of each project, so that we always test the exact same files regardless of how these projects grow over time.

Watching the react source code (small project)

The pinned version of react contains 1,554 files in 292 directories.

Windows

Library	Ready In	Retained Heap	Retained RSS
chokidar	1286.68ms	35.3 MB	48 MB
gaze	1006.31ms	16 MB	15.5 MB
watchboy	290.58ms	15.9 MB	19.3 MB

Linux

Library	Ready In	Retained Heap	Retained RSS
chokidar	636.64ms	35.2 MB	43.3 MB
gaze	441.16ms	17.3 MB	17.2 MB
watchboy	262.26ms	16 MB	19 MB

MacOS

Library	Ready In	Retained Heap	Retained RSS
chokidar	271.03ms	15.9 MB	21.2 MB
gaze	639.29ms	17.6 MB	15.2 MB
watchboy	287.46ms	16.6 MB	20.8 MB

Watching the vscode source code (medium project)

The pinned version of vscode contains 4,396 files in 1,399 directories.

Windows

Library	Ready In	Retained Heap	Retained RSS
chokidar	4063.48ms	53.3 MB	90.5 MB
gaze	3221.65ms	38.7 MB	63.4 MB
watchboy	868.90ms	19.5 MB	21.5 MB

Linux

Library	Ready In	Retained Heap	Retained RSS
chokidar	1787.42ms	52 MB	65.7 MB
gaze	1074.02ms	43.7 MB	55.5 MB
watchboy	846.60ms	31.2 MB	25.7 MB

MacOS

Library	Ready In	Retained Heap	Retained RSS
chokidar	717.89ms	39.2 MB	49.1 MB
gaze	1531.37ms	39.3 MB	48.2 MB
watchboy	717.92ms	34.7 MB	23.8 MB

Watching the babel source code (large project)

The pinned version of the babel source code is pretty diabolical. It contains 16,528 files in 8,216 directories. I actually had to disqualify gaze from this benchmark because it throws a Maximum call stack size exceeded when trying to watch all files.

Windows

Library	Ready In	Retained Heap	Retained RSS
chokidar	18936.22ms	164 MB	304 MB
watchboy	7408.11ms	49.2 MB	54.2 MB

Linux

Library	Ready In	Retained Heap	Retained RSS
chokidar	7728.19ms	181 MB	208 MB
watchboy	6865.25ms	63.5 MB	70.9 MB

MacOS

Library	Ready In	Retained Heap	Retained RSS
chokidar	2957.61ms	67 MB	97.6 MB
watchboy	5524.79ms	51.1 MB	59.9 MB

Watching a single large directory

This case is not necessarily common in software, but is common with other use cases. For a [photography application] I maintain, it is not all that rare to open a single directory with several hundred to a couple thousand photos that you took on a single day or single trip. In this benchmark, we'll watch a 1 directory containing 2000 files.

Windows

Library	Ready In	Retained Heap	Retained RSS
chokidar	899.83ms	36.9 MB	49.2 MB
gaze	31861.00ms	15.2 MB	12.9 MB
watchboy	172.60ms	13.6 MB	17.8 MB

Linux

Library	Ready In	Retained Heap	Retained RSS
chokidar	432.60ms	37.5 MB	44.7 MB
gaze	42522.20ms	15.3 MB	22.1 MB
watchboy	146.25ms	13.6 MB	19.8 MB

MacOS

Library	Ready In	Retained Heap	Retained RSS
chokidar	225.75ms	16.9 MB	22.5 MB
gaze	52723.25ms	8.65 MB	12.3 MB
watchboy	213.00ms	15.9 MB	21.3 MB

Memory footprint

This one is more for fun, but I wanted to see how much memory is needed to simply require each module and have it be present at runtime. Here's the breakdown:

Library	Windows size	Linux size	MacOS size
chokidar	1.63 MB	1.59 MB	2.34 MB
gaze	3.29 MB	2.45 MB	4.99 MB
watchboy	1.56 MB	1.75 MB	2.14 MB

Download size

An extension of the footprint, this metric measures how many files are installed as a result of each dependency, as well as the total size of each dependency.

Library	Packages	Directories	Files	Total size
chokidar (Windows)	14	18	78	339 kB
chokidar (MacOS)	15	19	83	374 kB
gaze	14	19	1111	1.6 MB
watchboy	12	15	72	342 kB

Run the benchmarks yourself

The results presented here are from pipeline runs in Azure Pipelines. There are pipelines in Travis-CI as well, showing comparable results. You can also run them yourself on your own machine if you'd like:

git clone https://github.com/catdad-experiments/filewatch-benchmarks.git
cd filewatch-benchmarks
npm install

# run all benchmarks
npm start

# get the names of all available benchmarks
npm run testlist

# run only a single test from the above list
npm start -- <test name>

All the tests themselves are defined in the benchmarks directory.

The benchmarks are powered by grandma. If you want to see a different test, feel free to add it and send me a PR.