Bug: Memory Leak with watch mode --watch=true

[mxschmitt]

Reproduction:

1. git clone https://github.com/microsoft/playwright && cd playwright
2. npm ci
3. npx esbuild --log-level=verbose "packages/playwright-core/src/**/*.ts" --outdir=packages/playwright-core/lib --sourcemap=linked --watch=true --platform=node --format=cjs
4. Go to packages/playwright-core/src/client/page.ts and modify the file header 20 times, between each time save the file and look at the memory consumption.

This can be used as well:

import fs from "fs"
for (let i = 0; i < 100; i++) {
  fs.appendFileSync("packages/playwright-core/src/client/page.ts", "\n")
  await new Promise((resolve) => setTimeout(resolve, 50))
}

and aborted after a few seconds.

Expected: It stays around 50-200 MB
Actual: It grows up to 10-40 GB

Version: 0.25.0 - also tested with 0.25.2

I was able to reproduce on macOS and Linux (Ubuntu amd64).

[mxschmitt]

Investigation:

• We are doing --watch=true
• Internally if --watch is not passed, GC is disabled as per here:

  • esbuild/cmd/esbuild/main.go

    Line 316 in 44e7469

    debug.SetGCPercent(-1)

• Changing it from --watch=true to --watch fixes it

[evanw]

Thanks for figuring this out, and for the PR. Quite a dumb bug. I'll include the fix for this in the next release.