How do I debug memory issues?

[jhage-snapsheet]

We have successfully migrated to rsbuild in production, and can build in local in ~5 seconds (without lazy). However, rstest seems to use my full 64GB of RAM and then crashes with out of memory error. How can I properly debug what exactly is going on?

When I run rstest on a specific folder with much less tests, it uses a lot of memory sure but doesn't crash. Perhaps we are causing a memory leak somewhere on our end. I could use some help debugging

I have done things from rspack suggestion like remove minimizer and parallel processing

Thank you!!

[9aoy]

Sorry to hear that you're facing memory issues with rstest.

Some information may be helpful:

• We fixed a memory leak issue in rstest v0.5.2. fix: out-of-memory in large project #621
• logHeapUsage is supported in rstest v0.6.2. After setting logHeapUsage to true, Rstest will log heap usage for each test.

To debug the memory issue with rstest, you can take a heap snapshot to analyze the memory usage.

node --heap-prof  --heap-prof-dir=./heap-prof ./node_modules/@rstest/core/bin/rstest.js

node --inspect ./node_modules/@rstest/core/bin/rstest.js watch

[jhage-snapsheet]

As far as I can tell the watch command works, but the normal command crashes out of memory before a test even starts running. Seems to be in the compile step.

When I try to inspect the heap with NODE_OPTIONS="--heapsnapshot-near-heap-limit=1" it seems to have gigabytes full of strings, like 75MB a piece

This is our config

{
    testEnvironment: 'jsdom' as const,
    setupFiles: ['./test/helpers/setup.js'],
    globals: true,
    plugins: [
      pluginNodePolyfill(),
      pluginReact(),
    ],
    tools: {
      rspack: {
        experiments: {
          parallelCodeSplitting: false,
        },
        resolveLoader: {
          alias: {
            // Modify the resolution of worker-loader in the inline loader
            // such as `worker-loader!pdfjs-dist/es5/build/pdf.worker.js`
            "worker-loader": require.resolve("worker-rspack-loader"),
          },
        },
        optimization: {
          minimize: false,
        },
        plugins: [
          new DefinePlugin({
            ...(rsbuildConfig.source?.define ?? { ENV: {} }),
            jest: 'rstest',
          }),
        ],
      }
    },
    resolve: {
      alias: pathAliases
    }
  }

Why would source maps be included? Or is that a misleading name?

When I view the dist/.rstest-temp/.rsbuild/rspack.config.rstest.mjs I see we have about ~1500 files between src and test which sounds right

[9aoy]

Could you provide a reproducible repository?
The existence of sourcemap files is reasonable because rstest needs them to locate the source code.
By default, rstest bundles all dependencies in the jsdom environment, which may result in excessively large outputs causing OOM issue. You can try to use output.externals to configure which dependencies are not bundled.