deno/tools/faster-rebuilds.md

Faster rebuilds with cargo-plonk

This document describes how to use cargo plonk to speed up Deno rebuilds for faster dev cycles.

cargo install cargo-plonk

How it works

Plonk works by hot swapping symbols using a fresh dynamic library of the local crates.

Usage

First, compile Deno normally.

cargo build -p deno [--release]

Run the following command to start watching for changes in ext/webgpu crate and hot swap init_ops_and_esm function into the previously built deno bin.

cargo plonk run \
  --package deno_webgpu \
  --symbol init_ops_and_esm \
  --bin deno \
  --watch

Important:

Currently, this will only works for symbols that have been "materialized" in their crates. Cross-crate generics will not work.

You can use cargo plonk run to re-run commands on changes.

cargo plonk run -v \
  -p deno_webgpu \
  -s init_ops_and_esm \
  -b deno \
  --watch \
  -- eval "await navigator.gpu.requestAdapter()" --unstable

Comparing incremental compile times for ext/webgpu on Mac M1:

profile	cargo build	cargo plonk build
debug	42 s	0.5s
release	5 mins 12 s	2s

Debugging

Use the -v/--verbose flag to turn on debug info.

    Finished dev [unoptimized + debuginfo] target(s) in 8.86s
[*] Running: DYLD_INSERT_LIBRARIES="/Users/divy/gh/plonk/target/release/build/cargo-plonk-dd0f08c90ca82109/out/inject.dylib" DYLD_LIBRARY_PATH="/Users/divy/.rustup/toolchains/1.75.0-aarch64-apple-darwin/lib" NEW_SYMBOL="_ZN11deno_webgpu11deno_webgpu16init_ops_and_esm17h683ed96f45027bc1E" PLONK_BINARY="/Users/divy/gh/deno/target/debug/deno" PLONK_LIBRARY="/Users/divy/gh/deno/target/debug/libdeno_webgpu.dylib" SYMBOL="_ZN11deno_webgpu11deno_webgpu16init_ops_and_esm17h6907fcd8be7e215eE" VERBOSE="y" "/Users/divy/gh/deno/target/debug/deno" "eval" "await navigator.gpu.requestAdapter()" "--unstable"
[*] Plonking _ZN11deno_webgpu11deno_webgpu16init_ops_and_esm17h6907fcd8be7e215eE in /Users/divy/gh/deno/target/debug/libdeno_webgpu.dylib
[*] Old address: 0x105fcff2c
[*] New address: 0x128511424
===

Report any bugs and feature requests in the cargo-plonk issue tracker: https://github.com/littledivy/plonk/issues/new