Common Profiling Steps

If you have a problem with SWC minifier about memory allocation and you are on mac, you can use ddt (opens in a new tab) to profile the memory usage. Also, many steps are common to any kind of profiling.

Step 1. Prepare the inputs

If you want to check the example directory for inputs, you can take a look at https://github.com/kdy1/swc-minifier-inputs (opens in a new tab). These input files are extracted from real next.js projects publicly available on github. See debugging-nextjs-app for more details.

In this example, we will assume that the link above is cloned to ~/projects/minifier-inputs. (i.e. git clone https://github.com/kdy1/swc-minifier-inputs.git ~/projects/minifier-inputs)

Replace ~/projects/minifier-inputs in the commands below with the directory containing your input files. It can be either a file or a directory containing the input files. All .js files will be minified, without writing the result to the disk.

Step 2. Clone the repository

git clone https://github.com/swc-project/swc.git
cd ./swc/crates/swc_ecma_minifier

Profiling Time Usage

Step 3. Run the profiler

You have two options. One is to use samply, which is cross-platform, and the other is to use XCode Instruments, which is only available on mac.

Using samply

CARGO_PROFILE_RELEASE_DEBUG=1 RUST_LOG=off ddt profile samply cargo --release --features concurrent --example minify-all -- ~/projects/minifier-inputs  to the directory containing your input files. It can be either a file or a directory containing the input files. All .js files will be minified (without writing the result to the disk)

This will open a tab in your browser once the profiling is done.

Using XCode Instruments

CARGO_PROFILE_RELEASE_DEBUG=1 RUST_LOG=off ddt profile instruments cargo -t time --release --features concurrent --example minify-all -- ~/projects/minifier-inputs  to the directory containing your input files. It can be either a file or a directory containing the input files. All .js files will be minified (without writing the result to the disk)

This will open the Instruments app once the profiling is done.

Profiling Memory Usage

Step 3. Run the profiler

The command to run the profiler is as follows:

CARGO_PROFILE_RELEASE_DEBUG=1 RUST_LOG=off ddt profile instruments cargo -t 'Memory' --release --features concurrent --example minify-all -- ~/projects/minifier-inputs  to the directory containing your input files. It can be either a file or a directory containing the input files. All .js files will be minified (without writing the result to the disk)

This will open the Instruments app once the profiling is done.