de5b47b13c
While investigating poor cold start performance on my GCP VM (32 cores,
130GB SSD), I found that writing to the various sqlite databases in
DENO_DIR was quite slow. The slowness seems to primarily be caused by
excessive latency from a number of `fsync()` calls.
The performance difference is best demonstrated by deleting the sqlite
databases from DENO_DIR while leaving the downloaded sources in place.
The benchmark (see notes below):
```
piscisaureus@bert-us:~/erofs/source$ export DENO_DIR=./.deno
piscisaureus@bert-us:~/erofs/source$ hyperfine --warmup 3 \
--prepare "rm -rf .deno/*_v1*" \
"deno run -A --cached-only demo.ts" \
"eatmydata deno run -A --cached-only demo.ts" \
"~/deno/target/release/deno run -A --cached-only demo.ts"
Benchmark 1: deno run -A --cached-only demo.ts
Time (mean ± σ): 1.174 s ± 0.037 s [User: 0.153 s, System: 0.184 s]
Range (min … max): 1.104 s … 1.212 s 10 runs
Benchmark 2: eatmydata deno run -A --cached-only demo.ts
Time (mean ± σ): 265.5 ms ± 3.6 ms [User: 138.5 ms, System: 135.1 ms]
Range (min … max): 260.6 ms … 271.2 ms 11 runs
Benchmark 3: ~/deno/target/release/deno run -A --cached-only demo.ts
Time (mean ± σ): 226.2 ms ± 9.2 ms [User: 136.7 ms, System: 93.3 ms]
Range (min … max): 218.8 ms … 247.1 ms 13 runs
Summary
~/deno/target/release/deno run -A --cached-only demo.ts ran
1.17 ± 0.05 times faster than eatmydata deno run -A --cached-only demo.ts
5.19 ± 0.27 times faster than deno run -A --cached-only demo.ts
```
Notes:
* Benchmark 1: unmodified Deno 1.43.6
* Benchmark 2: unmodified Deno 1.43.6 wrapped with `eatmydata` (which is
a tool to neuter `fsync()` calls)
* Benchmark 3: this PR applied on top of Deno 1.43.6
The script that got benchmarked:
```typescript
// demo.ts
import * as express from "npm:express@4.16.3";
import * as postgres from "https://deno.land/x/postgres/mod.ts";
let _dummy = [express, postgres]; // Force use of imports.
console.log("hello world");
```
|
||
|---|---|---|
| .cargo | ||
| .devcontainer | ||
| .github | ||
| bench_util | ||
| cli | ||
| ext | ||
| runtime | ||
| tests | ||
| tools | ||
| .dlint.json | ||
| .dprint.json | ||
| .editorconfig | ||
| .gitattributes | ||
| .gitignore | ||
| .gitmodules | ||
| .rustfmt.toml | ||
| Cargo.lock | ||
| Cargo.toml | ||
| LICENSE.md | ||
| README.md | ||
| Releases.md | ||
| rust-toolchain.toml | ||
Deno
Deno
(/ˈdiːnoʊ/, pronounced
dee-no) is a JavaScript, TypeScript, and WebAssembly runtime with secure
defaults and a great developer experience. It's built on V8,
Rust, and Tokio.
Learn more about the Deno runtime in the documentation.
Installation
Install the Deno runtime on your system using one of the commands below. Note that there are a number of ways to install Deno - a comprehensive list of installation options can be found here.
Shell (Mac, Linux):
curl -fsSL https://deno.land/install.sh | sh
PowerShell (Windows):
irm https://deno.land/install.ps1 | iex
Homebrew (Mac):
brew install deno
Chocolatey (Windows):
choco install deno
Build and install from source
Complete instructions for building Deno from source can be found in the manual here.
Your first Deno program
Deno can be used for many different applications, but is most commonly used to
build web servers. Create a file called server.ts and include the following
TypeScript code:
Deno.serve((_req: Request) => {
return new Response("Hello, world!");
});
Run your server with the following command:
deno run --allow-net server.ts
This should start a local web server on http://localhost:8000.
Learn more about writing and running Deno programs in the docs.
Additional resources
- Deno Docs: official guides and reference docs for the Deno runtime, Deno Deploy, and beyond.
- Deno Standard Library: officially supported common utilities for Deno programs.
- deno.land/x: registry for third-party Deno modules.
- Developer Blog: Product updates, tutorials, and more from the Deno team.
Contributing
We appreciate your help! To contribute, please read our contributing instructions.